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MARCH,  1921 


MEMOIR  39 


CORNELL  UNIVERSITY 
AGRICULTURAL  EXPERIMENT  STATION 


THE  GENETIC  RELATIONS  OF  PLANT  COLORS 

IN  MAIZE 


R.  A.  EMERSON 


ITHACA,  NEW  YORK 
PUBLISHED  BY  THE  UNIVERSITY 


MARCH,  1921  MEMOIR  39 


CORNELL  UNIVERSITY 
AGRICULTURAL  EXPERIMENT  STATION 


THE  GENETIC  RELATIONS  OF  PLANT  COLORS 

IN  MAIZE 


R.  A.  EMERSON 


ITHACA,  NEW  YORK 
PUBLISHED  BY  THE  UNIVERSITY 


CONTENTS 

PAGE 

Previous  investigations 8 

Source  and  description  of  materials  used 9 

Purple,  type  1 9 

Sun  red,  type  II 1 1 

Dilute  purple,  type  III ll 

Dilute  sun  red,  type  IV 12 

Brown,  type  V 14 

Green,  type  VI 14 

Relation  of  plant  colors  to  environment 15 

Sunlight  a  factor  in  color  development 16 

Moisture  in  relation  to  color 18 

Temperature  in  relation  to  color 19 

Soil  fertility  and  color  development 21 

Rich  compared  with  poor  soil 21 

Lack  of  particular  nutrient  elements 23 

Relation  of  carbohydrates  to  color 26 

Summary 28 

Genetic  analysis  of  color  types 29 

Crosses  invohong  the  factor  pairs  A  a,  Bb,  PI  pi 29 

Purple  la  x  green  VIc 29 

Dilute  sun  red  I\'a  x  brown  V 32 

Backcrosses  of  la  x  \'Ic  and  YVa,  x  V  with  IVa 34 

Behavior  of  F2  color  types  in  later  generations 35 

Intercrosses  of  F2  color  types 48 

Evidence  from  aleurone-color  and  linkage  relations 58 

Summary  of  results  invohdng  A  a,  Bb,  PI  pi 64 

Crosses  involving  the  multiple  allelomorphs  B,  B"',  b^,b 65 

Interrelations  of  sun  red  I  la,  weak  sun  red  lib,  and  dilute  sun  red  IVa 67 

Relation  of  weak  purple  lb  to  purple  la,  dilute  purple  Illa,  and  weak  sun  red  lib 69 

Crosses  involving  the  multiple  allelomorphs  R'^,  R^,  R''3^  r*",  r",  r-*^'* 73 

Green  IVg  x  brown  V 74 

Intercrosses  of  F2  color  types 86 

Purple  la  x  green -ant  her  ed  dilute  sun  red Ill 

Summary  of  results  involving  the  allelomorphic  series  R^,  Ro,  R^,  r'',  ro,  r^^ 112 

Relation  of  aleurone  factors  C  c  and  Prpr  to  plant  color 113 

Ex-pression  of  plant-color  and  aleurone-color  factors 114 

Summary 118 

Literature  cited 120 

Appendix  (containing  tables) 121 


THE  GENETIC  RELATIONS  OF  PLANT  COLORS  IN  MAIZE 


THE  GENETIC  RELATIONS  OF  PLANT  COLORS  IN  MAIZE^ 

R.  A.  Emerson 

Under  the  designation  "  plant  colors  "  are  included  the  colors  other  than 
those  related  to  chlorophyll,  commonly  seen  in,  but  not  limited  to,  such 
external  plant  parts  of  maize  as  the  culm,  the  staminate  inflorescence, 
the  husks,  the  leaf  sheaths,  and  to  some  extent  the  leaf  blades.  In  con- 
trast to  this  group  are  colors  and  color  patterns  related  to  chlorophyll  or 
associated  with  the  pericarp  and  the  cob,  the  silks,  the  endosperm,  the 
alem'one.  The  colors  included  in  the  group  considered  here  are  due  to 
water-soluble  pigments,  but  the  same  is  true  of  some  of  the  other  color 
groups  named  above.  Moreover,  colors  of  the  chlorophyll  group  (Lind- 
strom,  1918)  are  found  in  the  same  plant  parts  as  are  the  "  plant  "  colors 
considered  in  this  account.  The  plant  colors  as  a  whole  are  closely 
interrelated,  but  they  are  closely  related  also  to  aleurone  colors  and  to 
certain  of  the  silk  and  pericarp  colors.  It  is  obvious,  therefore,  that, 
while  this  classification  is  a  more  or  less  natural  one,  it  is  based  primarily 
on  convenience. 

The  term  "  genetic  relations  "  in  the  title  to  this  memoir  is  to  include 
not  merely  an  account  of  the  genetic  analysis  of  the  material  at  hand  by 
means  of  hybridization  experiments  —  tho  that  constitutes  the  greater 
part  of  the  paper  —  but  also  some  consideration  of  the  variations  of  the 
several  color  types  induced  by  or  associated  with  environmental  diver- 
sities. Some  httle  attention  to  matters  of  this  kind  was  made  necessary 
by  the  fact  that  presmnably  homozygous  material  exhibited  marked 
variations  in  extent  and  intensity  of  pigmentation  when  grown  under  diverse 
conditions.  Since,  as  will  be  apparent  later,  the  principal  differences 
between  certain  of  the  color  types  under  investigation  are  apparently 
quantitative  ones,  and  since  the  materials  at  best  exhibit  no  little  complex- 
ity with  respect  to  factorial  interrelations  of  a  genetic  nature,  little  progress 
could  have  been  made  without  some  notion  of  the  response  of  particular 
color  types  to  certain  factors  of  the  environment.     But  this  study  has 

'  Paper  No.  78,  Department  of  Plant  Breeding,  Cornell  University,  Ithaca,  New  York. 

7 


8  R.  A.  Emerson 

been  wholly  subsidiary  to  the  main  purpose,  namely,  a  genotypic  analysis 
of  the  color  types  under  observation.  The  writer's  realization  of  the 
superficial  nature  of  the  environmental  studies  reported  in  this  account 
in  no  way  weakens  his  belief  in  the  importance  of  acquiring  an  accurate 
knowledge  of  the  chemistry  of  the  pigments  concerned  and  of  instituting 
fundamental  investigations  into  the  physiology  of  their  development  — 
problems  that  must  await  the  interest  and  effort  of  other  workers. 

The  studies  reported  here  were  begun  in  a  small  way  in  1909  and  have 
been  continued,  along  with  other  problems  in  the  genetics  of  maize,  to 
the  present  time.  The  work  was  conducted  at  the  University  of  Nebraska 
and  supported  by  funds  of  that  institution  from  1909  to  1914.  During 
1911  facilities  for  growing  and  studying  a  considerable  part  of  the  cultures 
then  in  hand  were  generously  afforded  the  writer  by  the  Bussey  Institu- 
tion at  Harvard  University.  Since  1914  the  work  has  been  conducted 
at  Cornell  University. 

During  these  years,  the  v/riter  has  been  assisted  by  a  number  of  persons, 
among  whom  he  desires  to  mention  particularly  Dr.  E.  W.  Lindstrom  and 
Dr.  E.  G.  Anderson.  Some  data  from  the  records  of  students  associated 
with  the  writer  are  included  in  this  account.  The  cultures  giving  these 
borrowed  data  are  indicated  in  the  tables  by  initial  letters  preceding  the 
pedigree  numbers,  as  follows:  A  =  E.  G.  Anderson,  L  =  E.  W.  Lind- 
strom, and  S  =  Sterling  H.  Emerson. 

The  illustrations  are  from  water-color  drawings  by  C.  W.  Redwood, 
Miss  Carrie  M.  Preston,  and  Miss  Bernice  M.  Branson. 

PREVIOUS  INVESTIGATIONS 

So  far  as  the  writer  is  aware,  little  work  with  the  plant  colors  of  maize 
has  been  reported  previous  to  this  time.  Webber  (1906)  reported  the 
results  of  studies  of  the  interrelations  of  aleurone,  silk,  anther,  and 
glume  colors,  with  the  conclusion  that  color  in  all  these  parts  is  closely 
correlated  but  that  there  are  definite  breaks  in  the  correlation.  This 
conclusion,  in  terms  of  present-day  usage,  is  apparently  equivalent  to 
the  idea  of  close  linkage  with  some  crossing-over.  East  and  Hayes  (1911) 
identified  certain  aleurone-color  genes,  which  are  shown  in  the  present 
account  to  be  related  to  plant  colors  as  well  as  to  aleurone  colors,  and 
reported  data  concerning  the  inheritance  of  silk  and  anther  colors.  The 
writer  (Emerson,  1918)  added  another  aleurone-color  pair  also  known  to 


Plant  Colors  in  Maize  9 

be  concerned  in  plant-color  development.  He  had  earlier  (191 1)  announced 
some  of  the  plant  colois  discussed  in  the  present  paper  and  placed  on 
record  some  evidence  as  to  their  genetic  behavior.  Gcrnert  (1912) 
described  types  of  maize  that  differ  widely  in  color  of  anthers,  glumes, 
silks,  sheaths,  and  husks,  and  reported  simple  mendelian  behavior  in  Fi 
and  Fo  of  certain  crosses.  With  this  exception,  Gernert's  extensive  investi- 
gation of  plant-color  types  has  not  been  reported,  but  the  writer  has  been 
able,  thru  an  exchange  of  material,  to  compare  some  of  Gernert's  types 
with  those  in  his  own  cultures. 

SOURCE  AND  DESCRIPTION  OF  MATERIALS  USED 

The  plant-color  types  discussed  in  this  paper  came  in  the  main  from 
the  crossing  of  two  little-known  varieties,  one  of  which  was  obtained  at  a 
national  corn  exposition  and  the  other  from  an  exhibit  at  a  local  agri- 
cultural fair.  One  of  the  color  types  produced  by  this  cross  is  the  same  as 
that  of  the  dent  varieties  generally  grown  thi-uout  the  Corn  Belt;  a  second 
is  not  infrequently  seen  in  certain  pop,  flint,  and  sweet  corn  varieties; 
and  a  third  occurs  in  the  fields  of  flour  corn  of  certain  Indian  tribes  of 
the  Southwest.  One  of  the  color  types  produced  by  the  cross  had  no 
existence,  so  far  as  the  writer  knows,  until  it  appeared  in  his  cultures. 
Modifications  of  several  of  the  six  color  types  noted  above  have  been 
produced  by  crossing  with  a  color  type  common  in  a  few  varieties  of 
sweet  corn  and  closely  related  to  the  type  most  common  in  field  maize. 
The  principal  color  types  concerned  in  this  account  are  discussed  in  some 
detail  in  the  descriptive  notes  below.     They  are: 

I  —  Purple 
II  —  Sun  red 

III  —  Dilute  purple 

IV  —  Dilute  sun  red 
V  —  Brown 

VI  —  Green 

PURPLE,    TYPE    I 

Material  of  the  purple  type  was  first  obtained  as  a  single  ear  from  a 
local  agricultural  fair  at  Nehawka,  Nebraska,  in  190G.  The  varietal 
name  is  unknown.     The  uncrossed  stock  was  a  smooth-seeded  pop  corn 


10  R.  A.  Emerson 

of  medium  size.  No  other  stock  of  purple  has  been  used  in  the  crosses 
described  later  in  this  account,  and  the  writer  has  never  seen  this  color 
type  in  cultivation  outside  his  own  cultures.  A  sample  of  dent  corn  of 
apparently  the  same  color  tj^e  was  seen  at  a  national  corn  exposition 
in  1909.  A  stock  of  purple  was  obtained  from  Dr.  Gernert  in  1914  but 
was  not  used  in  genetic  studies.  Another  stock  of  purple  was  received 
more  recently  (1919)  from  Messrs.  Collins  and  Kempton,  the  seed  having 
come  originally  from  Bolivia. 

Seedlings  of  the  purple  type  are  usually  indistinguishable  from  those  of 
types  II,  III,  and  IV  (described  more  fully  under  type  IVa,  page  12),altho, 
unUke  the  other  types,  they  develop  some  color  when  grown  in  darkness. 
Half-grown  plants  of  type  I  usually  have  the  lower  sheaths  prominently 
colored,  in  which  respect  they  exceed  type  II  plants  in  intensity  of  pig- 
mentation and  are  sharply  differentiated  from  types  III  and  IV.  At  the 
flowering  stage,  plants  of  type  la  have  much  purple  color  in  nearly  all 
parts,  such  as  the  cuhn,  the  brace  roots,  the  leaf  sheaths,  the  husks  —  even 
the  inner  ones  —  the  cob,  and  the  staminate  inflorescence  including  the 
rachis,  the  spikelets,  and  the  anthers  (Plates  I,  1,  and  V,  1).  In  some 
cases  the  color  extends  over  the  whole  leaf,  and  it  is  always  seen  in 
the  midrib.  The  purple  pigment  of  type  la  develops  in  local  darkness, 
as  has  been  shown  by  covering  various  parts  of  growing  plants  with  several 
thicknesses  of  heavy  black  paper  (Plate  VIII,  1).  The  color  persists  in 
mature  plants  with  slight  fading  in  the  outer  parts  due  to  weathering  (Plate 
VII,  1).  The  pericarp  of  type  la  is  either  colorless,  red,  or  cherry,  and 
the  aleurone  is  either  purple,  red,  or  colorless.  With  red  aleurone  the 
anthers  are  reddish  purple,  and  with  cherry  pericarp  they  are  usually 
very  dark  purple,  almost  black  (Plate  I.  2  and  3). 

A  subtype  of  purple  known  as  weak  purple,  or  type  lb,  is  similar  to  la 
but  the  pigmentation  is  less  intense,  particularly  in  the  cuhn  and  the 
inner  husks  (Plate  V,  2).  In  early  stages  of  growth  it  is  often  difficult 
to  distinguish  lb  from  Ha.  The  anthers  of  lb  are  usually  deep  purple, 
as  are  those  of  la,  and  the  pericarp  is  the  same  as  for  la.  Another  sub- 
class of  purple,  Ig,  is  like  la  except  that  the  anthers  are  green  (Plate  I, 
4)  and  the  pericarp  is  red  or  colorless,  never  cherry.  The  aleurone  color 
is  the  same  as  in  la. 


Plant  Colors  in  Maize  11 

sun  red,  type  ii 

Sun  red,  the  not  a  common  color  type,  is  encountered  in  a  few  varieties 
of  sweet  corn  and  pop  corn.  It  is  always  produced  in  F2  of  certain  crosses, 
notably  in  purple  x  green. 

While  this  type  is  less  highly  colored  than  la,  it  has  such  strong  color 
that  it  is  not  easily  distinguished  from  the  latter  in  early  stages  of  growth. 
At  the  flowering  stage,  type  Ila  is  sharply  differentiated  from  type  la  in 
several  respects.  The  staminate  inflorescence  of  Ila  is  lighter  than  that 
of  la,  and  the  anthers  are  deep  pink  instead  of  purple  (Plate  III,  1).  In 
type  Ila,  pigmentation  of  the  cuhn,  the  leaf  sheaths,  and  the  husks  is 
limited  almost  wholly  to  parts  exposed  to  sunlight,  hence  the  name  sun 
red.  The  inner  husks  are  therefore  without  red  color,  and  rarely  does 
much  color  develop  in  any  but  the  outer  layer  of  husks  (Plate  V,  3)  not- 
withstanding the  fact  that  sufficient  light  penetrates  to  the  inner  husks  to 
induce  the  development  of  some  chlorophyll  in  them.  A  tassel  inclosed 
in  a  black  paper  bag  produces  no  red  color  in  either  glumes  or  anthers 
(Plate  VIII,  4).  Since  the  color  of  sun  red  plants  is  so  largely  superficial, 
it  disappears  almost  wholly  from  mature  plants  thru  weathering  (Plate 
VII,  2).  Sun  red  plants  have  either  red  or  colorless,  but  never  cherry, 
pericarp,  and  either  purple,  red,  or  colorless  aleurone. 

Sun  red  of  type  Ilg  differs  from  Ila  merely  in  having  green  instead  of 
pink  anthers.  Type  lib,  known  as  weak  sun  red,  differs  from  Ila  in  the 
lesser  intensity  and  extent  of  its  pigmentation.  Particularly  the  leaf 
sheaths  and  the  husks  are  less  highl}^  colored  than  in  type  Ila.  Often 
the  color  of  the  husks  develops  in  alternate  dark  and  light  bars  parallel 
to  the  upper  margins  of  the  overlapping  husks  (Plate  V,  4).  Types  lib 
and  llg  have  the  same  pericarp  and  aleurone  colors  as  Ila. 

DILUTE    PURPLE,    TYPE    III 

The  dilute  purple  type,  as  well  as  the  sun  red,  occurs  regularly  in  F2 
of  purple  X  green,  and  most  of  the  dilute  purple  material  in  the  writer's 
cultures  came  originally  from  this  and  other  cro.sses.  It  was  first 
observ'ed  in  the  progeny  of  such  crosses  in  1909.  Recently  two  stocks  of 
this  color  type  have  been  received  from  G.  N.  Collins,  one  obtained  from 
the  Hopi  Indians  of  southwestern  United  States  and  the  other  from 
Bolivia. 


12  R.  A.  Emerson 

Seedlings  and  young  plants  of  type  Ilia  show  no  more  color  than  do 
those  of  type  IVa,  and  apparently  do  not  develop  color  in  darkness.  As 
the  plants  approach  the  flowering  stage,  they  usually  show  somewhat 
more  color  than  do  plants  of  type  IVa,  particularly  at  the  base  of  the  culm 
and  in  the  brace  roots,  and  sometimes  in  the  leaf  sheaths.  The  staminate 
inflorescence  is  usually,  tho  not  always,  somewhat  more  highly  colored 
than  that  of  type  IVa.  The  anthers  are  deep  purple,  like  those  of  type 
la  (Plate  II,  1).  With  red  aleurone  the  anthers  are  usually  reddish  purple, 
and  with  cherry  pericarp  they  are  dark  purple,  sometimes  appearing 
nearly  black  (Plate  II,  2  and  3).  The  anther  color  develops  fully  in  dark- 
ness, but  the  glumes  are  slightly  if  at  all  colored  when  protected  from  light 
by  black  paper  bags  (Plate  VIII,  3).  As  the  plants  mature,  considerable 
color  develops  in  the  inner  husks  (Plate  VII,  3),  on  the  leaf  sheaths,  and 
particularly  in  the  culm  even  where  it  is  protected  from  strong  Ught  by 
the  sheaths.  In  some  cases  the  culm  and  the  sheaths  ultimately  become 
nearly  as  strongly  pigmented  as  type  la,  but  ordinarily  the  mature  plant 
is  considerably  less  highly  colored  than  the  purple  type  (Plate  VII,  4). 
The  color  seen  in  mature  plants  develops  well  in  local  darkness,  in  which 
respect  also  type  Ilia  is  hke  la.  Dilute  purple  differs  from  purple,  there- 
fore, mainly  in  a  less  intense  pigmentation  and  in  a  delayed  development 
of  pigment.  The  pericarp  of  type  Ilia  is  either  red,  cherry,  or  colorless, 
and  the  aleurone  is  either  purple,  red,  or  colorless,  just  as  in  type  la. 

There  exists  a  type  of  plant  color  which  is  closely  related  genetically 
to  type  Ilia,  but  which  lacks  red  or  purple  color  in  culm,  sheaths,  silks, 
glumes,  and  anthers  and  is  consequently  known  as  Green,  type  Illg 
(Plate  II,  4).  The  aleurone  of  this  type  is  either  purple,  red,  or  colorless, 
and  the  pericarp  is  either  red  or  colorless,  never  cherry.  With  respect 
to  aleurone  and  pericarp,  therefore,  type  Illg  is  like  type  Ig. 

DILUTE    SUN   RED,    TYPE    IV 

Dilute  sun  red  is  the  commonest  color  type  of  maize  in  cultivation.  It  is 
practically  the  only  color  type  seen  in  the  dent  varieties  grown  in  the  Corn 
Belt  of  the  United  States,  and  is  common  in  flint,  flour,  sweet,  and  pop 
corns.  Like  the  sun  red  and  the  dilute  purple  types,  it  always  appears 
in  crosses  of  purple  la  with  green  Vic. 

The  seedlings  of  type  IVa  usually  show  more  or  less  sun  red  pigment 
in  the  coleoptile,   the  leaf  sheath,   and  the  leaf  margins.     The  young 


Plant  Colors  in  Maize  13 

plants  ordinarily  have  considerable  color  at  the  base  of  the  lower  sheaths, 
but  little  or  no  color  except  green  in  other  parts  except  in  the  margins  of 
the  leaves  (Plate  IX.  1).  When  the  plants  are  grown  on  infertile  soil, 
much  bright  red  color  develops  in  all  parts  exposed  to  light  except  the 
youngest  leaves  (Plate  IX,  2).  The  seedlings  and  the  very  young  plants 
are  not  ordinarily  distinguishable  from  those  of  types  la,  Ila,  and  Ilia. 
Some  time  before  the  flowering  stage,  the  plants  of  this  type  are  sharply 
differentiated  from  those  of  types  la  and  Ila,  and  are  usually  somewhat 
less  highly  colored  than  those  of  type  Ilia.  In  normally  grown  plants, 
the  color  is  confined  mostly  to  the  brace  roots,  and  to  the  sheaths  and  the 
exposed  parts  of  the  culm  at  the  base  of  the  plants.  Even  at  the  flowering 
stage  almost  no  color  is  seen  in  the  upper  sheaths  or  the  upper  part  of  the 
culm,  and  very  Uttle  in  the  husks  (Plate  VI,  1).  The  staminate  inflores- 
cense  is  colored  much  as  is  that  of  the  sun  red  type,  tho  the  glumes  are 
lighter  than  those  of  type  Ila  and  the  rachis  is  usually  nearly  devoid  of 
color.  The  anthers  show  more  or  less  pink,  as  do  those  of  type  Ila. 
There  is  much  variation  in  the  extent  and  intensity  of  pigmentation  of 
glumes  and  anthers  (Plate  III,  2,  3,  and  4),  due  in  part  to  genetic  differ- 
ences and  in  part  probably  to  environmental  influences.  Late  in  the 
life  of  the  plant,  type  IVa  usually  shows  some  color  in  the  outer  husks  and 
also  in  exposed  parts  of  the  culm.  Different  strains  show  considerable 
variation  in  this  respect  (Plate  VI,  1  and  2).  Due  to  the  slight  develop- 
ment of  pigment  and  because  of  weathering,  the  dry  parts  of  mature 
plants  show  little  red  color  (Plate  VII,  6).  Light  is  essential  to  the 
development  of  color  in  dilute  sun  red,  IVa,  just  as  in  sun  red,  Ila.  The 
aleurone  and  pericarp  colors  of  dilute  sun  red,  IVa,  are  the  same  as  those 
of  sun  red,  ITa. 

A  wholly  green  type,  that  is,  one  devoid  of  pigment  other  than  green 
in  the  plant  parts  here  under  consideration,  is  closely  related  genetically 
to  type  IVa  and  is  therefore  known  as  type  IVg  (Plate  II,  4).  Phenotypi- 
cally  it  is  the  same  as  type  Illg.  Just  as  in  case  of  types  Ig,  II,  Illg,  and 
IVa,  the  pericarp  of  IVg  is  either  red  or  colorless,  never  cherry,  and  the 
aleurone  is  either  purple,  red,  or  colorless.  Genotypic  diversities  in  the 
amount  of  color  are  noted  for  type  IVa  above.  The  lightest  types  of 
dilute  sun  red  show  no  color  except  mere  traces  of  red  in  the  staminate 
spikelets.  This  condition  is  found  in  most  plants  of  at  least  two  varieties 
of  sweet  corn,  Black  Mexican  and  Crosby.     From  these  varieties  there 


14  R.  A.  Emerson 

have  been  isolated  strains  that  lack  even  this  minimum  of  color.  These 
strains  furnished  the  original  stock  of  type  IVg.  In  no  environment  as 
yet  encountered  has  any  red  or  purple  plant  color  developed  in  type  IVg. 

BROWN.    TYPE   V 

The  brown  type  was  first  seen  in  1912,  when  it  occurred  in  F2  of  the  cross 
purple  la  x  green  Vic.  So  far  as  the  writer  has  been  able  to  learn,  brown 
plant  color  had  not  been  reported  previously,  and  he  is  unaware  of  its 
existence  outside  of  his  own  cultures  or  of  stocks  grown  from  them. 

Seedlings  and  young  plants  of  type  V  are  wholly  green.  Before  the 
flowering  period  is  reached,  a  brown  pigment  begins  to  appear  in  the 
lower  sheaths.  At  the  time  of  flowering^  the  culm,  the  sheaths,  the 
husks  (Plate  VI,  3),  and  the  staminate  inflorescence  (Plate  IV,  1  and  2) 
are  brown.  The  anthers  are  usually  green.  The  brown  color  extends 
to  the  inner  husks,  to  the  culm  beneath  the  leaf  sheaths,  and  to  the  cob 
(Plate  VII,  5).  That  light  is  not  essential  to  the  development  of  brown 
is  shown  further  by  the  fact  that  the  color  appears  under  several  thick- 
nesses* of  black  paper  (Plate  VIII,  2).  It  is  not  uncommon  to  find  traces 
of  purple  associated  with  the  brown  in  the  brace  roots  and  at  the  base  of 
the  inner  husks  (Plate  VI,  3).  Abnormally  developed  tassels,  not  infre- 
quently seen  on  plants  grown  in  small  pots  in  the  greenhouse,  in  some 
cases  show  a  little  purple  (Plate  XI).  The  aleurone  of  brown  plants  is 
always  colorless,  except  for  xenia  grains,  and  the  pericarp  is  either  brown, 
brownish,  or  colorless,  never  red  nor  cherry.  Brown  pericarp  color  of 
type  V  corresponds  to  red  of  types  I,  II,  III,  and  IV,  and  brownish  to 
cherry  of  types  I  and  III. 

GREEN,    TYPE   VI 

The  writer's  stock  of  the  green  type  originated  from  a  single  ear  obtained 
at  a  national  corn  exposition  held  at  Omaha  in  1909.  The  corn  was 
exhibited  from  southern  Missouri,  where  it  is  grown  locally.  It  is  a 
large  dent  variety,  rather  late  in  season. 

Cultures  of  type  Vic,  derived  from  this  stock,  show  no  plant  color  other 
than  green  at  any  stage  of  development  or  under  any  environmental 
conditions  to  which  they  have  as  yet  been  subjected  (Plates  IV,  3,  and 
VI,  4). 


Plant  Colors  in  Maize  15 

•  Three  subclasses  of  type  VI  are  recognized.  One  of  these,  Via,  is  Hke 
Vic  in  every  respect  except  that  a  shght  amount  of  brown  is  sometimes 
seen  in  the  outer  husks  and  sheaths  (Plate  VI,  5).  The  second,  VIb.  is 
green  except  for  a  slight  tinge  of  brown  in  the  spikelets  of  the  staminate 
inflorescence  (Plate  IV,  4).  As  a  rule,  the  development  of  brown  pigment 
in  Via  and  VIb  is  not  sufficient  to  differentiate  with  certainty  the  one 
from  the  other,  or  either  from  Vic.  The  three  subclasses,  a,  b,  and  c, 
are  therefore  usually  classed  together  as  type  VI.  Both  Via  and  VIb 
have  been  isolated  from  crosses  involving  Vic.  The  aleurone  of  all  type 
VI  plants,  just  as  in  those  of  type  V,  is  colorless,  except  for  such  color  as 
may  be  due  to  xenia.  The  pericarp  of  Via  and  Vic  is  either  brown  or 
colorless,  never  brownish,  while  that  of  VIb  is  brown,  brownish,  or  color- 
less, as  in  the  case  of  type  V.  With  brownish  pericarp,,  type  VIb  usually 
shows  unmistakable  brown  color  in  the  staminate  spikelets. 

RELATION  OF  PLANT  COLORS  TO  ENVIRONMENT 

From  the  preceding  descriptive  notes  and  accompanying  illustrations, 
it  is  clear  that  many  of  the  differences  separating  the  six  major  color  types 
and  their  several  subclasses  are  quantitative.  Purple  plants  are  more 
strongly  colored  than  are  sun  red  or  dilute  purple  plants.  Dilute  sun 
red  plants  have  less  color  than  sun  red  or  purple  plants.  Weak  purple 
plants  have  less  color  than  purple  ones,  but  more  than  dilute  purple  ones, 
and  weak  sun  reds  are  intermediate  between  sun  reds  and  dilute  sun  reds. 
Dilute  sun  red  plants  vary,  from  those  showing  considerable  color  to  those 
which,  except  for  green,  are  nearly  colorless.  Wholly  green  plants  are 
classed  as  subgioups  of  both  dilute  purple  and  dilute  sun  red.  The 
subclasses  of  type  VI  differ  so  little  with  respect  to  color  that  they  are 
ordinarily  thrown  together  as  one  green  type.  Heterozygous  brown 
plants  are  lighter  than  homozygous  ones,  and,  since  more  than  one  factor 
pair  is  concerned;  there  is  a  fairly  smooth  gradation  from  the  darkest  to 
the  lightest  browns.  Plants  of  types  Via  and  VIb,  when  they  show  any 
brown,  differ  in  the  parts  colored.  The  color  of  the  staminate  inflores- 
cence, and  even  of  other  parts,  of  purples,  dilute  purples,  browns,  and 
greens  of  type  VIb  is  darker  when  the  pericarp  is  cherry  or  brownish  than 
when  it  is  red,  brown,  or  colorless. 

The  natural  intergrading  of  genetic  types  in  this  somewhat  complex 
series  is  often  made  still  more  confusing  by  the  variations  accompanying 


16  R.  A.  Emerson 

environmental  diversities.  A  prominent  geneticist,  on  observing  some 
of  the  writer's  cultures,  was  led  to  say  that  there  were  no  sharply  differ- 
entiating characteristics  by  which  other  than  an  arbitrary  classification 
could  be  made,  and  asserted  that  he  could  select  from  a  single  progeny  a 
series  grading  from  the  darkest  to  the  lightest  colors.  The  writer  has 
some  doubt  that  this  could  have  been  done,  but  the  instance  illustrates 
well  the  difficulties  that  confront  one  unacquainted  with  the  materials. 
It  is  fortunate  that  some  enviromnental  influences  which  increase  the 
difficulty  of  assorting  certain  color  types  make  other  types  stand  out  more 
sharply  than  they  otherwise  would.  Without  some  notion  of  these  envi- 
ronmental effects,  a  genetic  analysis  of  the  material  would  indeed  be 
difficult. 

SUNLIGHT   A   FACTOR   IN    COLOR   DEVELOPMENT 

The  relation  of  sunlight  to  the  development  of  color  has  been  noted 
briefly  in  the  descriptions  of  some  of  the  color  types.  The  effects  of 
sunlight  or  of  local  darkness,  instead  of  adding  to  the  confusion  of  color 
types,  afford  a  means  of  sharp  differentiation  between  certain  types. 
So  far  as  is  known  at  present,  no  color  develops  in  sun  red  or  dilute  sun 
red  plants,  or  in  the  early  stages  of  growth  of  dilute  purple  plants,  except 
under  the  influence  of  fairly  strong  light.  In  the  case  of  purple  and  of 
the  later  stages  of  growth  of  dilute  pm-ple,  there  is  no  doubt  that  the 
color  develops  more  rapidly  at  first  in  light  than  in  darkness,  but  ulti- 
mately color  develops  fully,  or  apparently  so,  even  in  local  darkness 
(Plate  VIII).  The  seedlings  of  purple  plants  develop  some  color  when 
germinated  and  grown  in  a  dark  chamber  where  no  part  of  the  plant  receives 
light.  There  is  some,  tho  very  little,  evidence  that  the  development  of 
brown  pigment  of  type  V  is  hastened  by  the  influence  of  light,  and  what 
little  brown  color  ever  develops  in  type  Via  is  confined  to  parts  exposed 
to  sunlight  (Plate  VI,,  5). 

It  would  not  be  surprising  to  find  that  the  pigments  seen  in  the  purple, 
dilute  purple,  sun  red,  and  dilute  sun  red  types  are  the  same  chemically. 
In  fact  they  look  alike  in  water  solution  and  apparently  react  in  the  same 
way  to  simple  chemical  tests.  If  they  prove  to  be  identical,  it  would  seem 
to  follow  that  purple  and  dilute  purple  plants  have  some  inherent 
mechanism,  perhaps  an  organic  catalyzer,  capable  of  initiating  or  hasten- 
ing chemical  reactions,  and  that  this  mechanism  is  lacking  in  sun  red 


Plant  Colors  in  Maize  17 

and  diluto  sun  rod  plants,  in  which  the  same  reactions  may  possibly  be 
brought  about  thru  the  action  of  sunlight. 

Usually  a  single  thickness  of  black  paper,  such  as  is  employed  to  pro- 
tect photographic  plates  from  light,  is  sufficient  to  prevent  the  develop- 
ment of  color  in  sun  red  plants  (Plate  VIII,  4).  That  more  intense  light 
is  necessary  for  the  production  of  sun  red  pigment  than  for  the  production 
of  chlorophyll  is  shown  by  the  ahnost  entire  absence  of  red  color  in  all 
but  the  outer  husks,  while  even  the  innermost  husks  are  somewhat  green 
(Plate  V,  3).  The  pigments  of  purple  and  brown  plants,  on  the  contrary, 
develop  well  even  when  there  is  too  little  light  for  the  formation  of  chloro- 
phyll (Plate  VIII,  1  and  2). 

That  the  effect  of  light  on  color  development  is  a  definitely  local  one  is 
shown  by  the  sharp  fine  of  demarcation  between  colored  and  colorless 
areas  in  culms,  husks,  and  sheaths  partly  exposed  and  partly  protected 
by  overlapping  sheaths  or  husks  (Plate  V,  3).  Even  a  single  piece  of 
wrapping  cord  tied  closely  about  a  young  ear,  sheath,  or  culm  of  a  sun 
red  plant  is  sufficient  to  prevent  the  development  of  color  beneath  it. 
Evidently  sun  red  pigment  does  not  diffuse  appreciably  from  the  cells  in 
which  it  forms.  It  is  not  meant  to  suggest  by  these  observations  that 
sunlight  has  no  effect  other  than  a  local  one  on  color  development.  On 
the  contrary,  there  is  evidence  that  the  development  of  sun  red  color  is 
influenced  bj^  the  presence  of  an  abundance  of  carbohydrates  which  in 
turn  are  dependent  on  sunlight  for  their  foraiation. 

A  striking  example  of  the  relation  of  sunlight  to  color  development  is 
afforded  by  the  barred  pattern  seen  in  the  husks  of  some  weak  sun  red 
plants  (Plate  V,  4).  The  pattern  consists  of  alternate  bars  of  red  and  green 
parallel  to  the  upper  margin  of  the  overlapping  husk  next  below  them.  By 
tracing  in  pencil  on  each  exposed  husk  of  a  rapidly  growing  ear  the  margin 
of  the  husk  overlapping  it,  it  has  been  ascertained  with  certainty  that  the 
red  bars  correspond  to  the  areas  that  are  pushed  out  from  under  the  over- 
lapping husk  between  early  morning  and  late  afternoon;  while  the  green 
bars  correspond  to  the  areas  pushed  ,out  during  the  late  afternoon  and 
night.  Why  color  develops  in  only  those  parts  of  the  husk  that  receive 
the  sunlight  when  first  exposed  to  the  air,  and  not  in  the  parts  exposed 
some  hours  previously,  is  not  known.  Another  illustration  of  the  effect  of 
sunlight  on  freshly  exposed  husks  was  seen  in  a  very  light  type  of  weak 
sun  red  (Plate  V,  5).    Of  two  ears  on  the  same  cuhn,  both  very  lightly 


18  R.  A.  Emerson 

and  about  equally  colored,  the  lower  had  its  husks  torn  apart  in  the  early 
forenoon  so  that  the  fresh  inner  husks  were  exposed  at  once  to  direct  sun- 
Ught.  In  a  few  hours  some  red  color  began  to  show,  and  in  a  few  days  all 
the  newly  exposed  husks  were  brilliantly  colored,  while  the  undisturbed 
upper  ear  remained  only  slightly  colored.  Similar  results  followed  in 
repeated  trials,  and,  in  fact,  failed  only  when  the  atmospheric  conditions 
were  such  as  to  cause  the  newly  exposed  husks  to  wither  during  the  first 
day.  It  is  of  interest  to  note  also  that  similarly  treated  ears  of  dilute 
sun  red  plants,  which  rarely  show  any  red  color  in  the  outer  husks  of  j^oung 
ears,  failed  to  develop  color  when  the  husks  were  torn  apart,  even  tho 
they  remained  fresh  for  some  daj^s. 

It  is  evident  from  all  this,  that,  with  respect  to  their  relation  to  sunlight, 
there  exists  a  series  of  color  t^q^es  varjdng  more  or  less  abruptly  from 
dilute  sun  red,  in  which  little  or  no  sun  red  develops  in  even  freshly  exposed 
husks,  thru  weak  sun  red,  in  which  color  fomis  in  only  freshly  exposed 
husks,  and  strong  sun  red,  in  which  much  color  develops  in  all  exposed 
parts  of  the  husks  but  not  in  parts  protected  from  light,  to  strong  purple, 
in  which,  tho  sunlight  may  hasten  color  development,  it  is  not  essential 
to  its  foraiation. 

Tests  of  the  influence  on  color  development  of  light  of  different  wave 
lengths  have  not  been  uniformly  successful.  Cramer  photographic  color 
screens  were  placed  in  partial  contact  with  the  uncolored  inner  husks  of 
sun  red  plants,  and  the  entrance  of  light  otherwise  than  thru  the  screens 
was  prevented  by  means  of  strips  of  black  paper.  These  screens,  by 
cutting  out  light  of  certain  wave  lengths,  not  only  change  the  quality  of 
Ught  passing  thru  them  but  lessen  the  intensitj''  of  the  light.  While  the 
results,  therefore,  can  have  Uttle  value,  it  may  be  of  interest  to  physiolo- 
gists to  note  that  considerable  sun  red  formed  under  the  orange  and  the 
bright  red  screens,  and  little  or  none  under  the  green  and  the  blue  screens. 

MOISTURE    IX   RELATION    TO    COLOR 

It  is  well  known  that  under  field  conditions  maize  does  not  grow  well  in 
wet  soil.  In  such  situations,  not  onl}'^  are  the  plants  small,  with  their 
leaves  pale  green,  but  they  often  develop  much  red  pigment.  The  writer 
has  repeatedly  observed  that  young  plants,  in  flooded  parts  of  fields  where 
the  soil  had  been  covered  with  water  for  some  days,  were  brilliantly  red 
in  all  parts  except  the  youngest  leaves,  while  near-by  plants  on  slightly 


Plant  Colors  ix  Maize  19 

higher  land  showed  only  the  slight  red  at  the  base  of  the  culms  character- 
istic of  young  dilute  sun  red  plants. 

For  a  study  of  the  effect  of  soil  moisture  on  color  development  under 
controlled  conditions,  plants  of  well-known  stocks  of  purple  la,  sun  red 
Ila,  dilute  purple  Ilia,  dilute  sun  red  IVa,  brown  V,  and  green  Vic  and 
IVg,  were  grown  in  rich  soil  in  earthen  jars  in  the  greenhouse  during 
the  summer  of  1914.  When  the  plants  had  reached  a  height  of  from 
10  to  15  centimeters,  the  jars  were  separated  into  three  lots — one  with 
dry  soil,  another  with  moist  soil,  and  a  third  with  wet  soil.  The  dry-soil 
lot  received  only  sufficient  water  to  keep  the  plants  growing  slowly  and  not 
enough  to  prevent  wilting  during  the  hotter  part  of  the  day.  The  moist- 
soil  lot  received  just  sufficient  water  to  insure  normal  growth.  The  wet- 
soil  lot  was  kept  constantly  in  saturated  soil  with  some  free  water  above  the 
soil  surface.  The  test  was  continued  until  the  plants  of  all  lots  reached 
the  flowering  stage. 

The  plants  in  moist  soil  made  the  most  rapid  growth  and  flowered  some- 
what earlier  than  the  plants  of  the  other  lots.  Their  leaves  were  of  normal 
green  color  and  they  showed  the  colors  characteristic  of  the  several  color 
types.  The  plants  in  dry  soil  were  smaller  and  very  dark  green.  The 
development  of  purple,  red,  and  l^rown  color  was  practically  the  same  as 
with  the  plants  in  moist  soil.  The  plants  in  wet  soil  grew  less  rapidly  than 
those  in  moist  soil,  but  more  rapidly  than  those  in  dry  soil.  Their  leaves 
were  somewhat  lighter  green  than  those  of  the  moist-soil  lot,  but  they 
showed  practically  the  same  amount  of  purple,  red,  and  brown  color.  In 
fact  the  only  differences  between  the  three  lots  with  respect  to  color  at 
any  time  during  the  test  were  such  as  might  well  be  related  to  the  stage  of 
development  of  the  plants.  All  color  types  show  more  color  in  the  later 
stages  of  growth.  The  moist-soil  lot  developed  somewhat  more  rapidly 
than  did  the  others  and  for  a  time  showed  slightly  more  color,  but  ulti- 
mately all  lots  had  practically  the  same  amount  of  color.  Evidently  the 
reddening  of  plants  iri  flooded  fields  is  not  due  directly  to  the  excess  of 
soil  moisture. 

TEMPERATURE  IN  RELATION  TO  COLOR 

Since  moisture  is  not  the  direct  cause  of  the  reddening  of  maize  plants 
in  flooded  fields,  tho  certainly  connected  with  the  phenomenon  in  some 
way,  it  follows  that  the  effect  must  be  produced  by  some  indirect  action 


20  R.  A.  Emerson 

of  the  excess  of  water.  Wet  soils  in  spring  are  cold  soils,  and  if  the  wet 
areas  are  of  considerable  extent  the  air  above  them  is  doubtless  somewhat 
cooler  than  that  above  drier  soil.  It  has  been  frequently  observed 
that  young  plants  which  show  much  color  during  a  cold  spring 
show  considerably  less  in  the  leaves  developed  after  the  weather  has  become 
wanner.  Young  plants  of  early-planted  maize  sometimes  have  more 
color  than  plants  that  are  started  later.  Moreover,  full-grown  plants 
from  late  plantings  often  develop  more  color  in  the  cool  weather  of  autumn 
than  similar  plants  that  mature  in  the  warm  weather  of  late  smiimer. 
It  seemed  important,  therefore,  to  study  the  effects  of  various  tempera- 
tures on  color  development. 

The  same  color  types  and  the  same  stocks —  in  one  test  the  identical 
plants —  used  in  the  soil-moisture  test  were  grown  in  the  greenhouse  under 
diverse  temperatures.  Altho  both  rich  and  poor  soils  of  diverse  water 
content  were  used,  the  comparisons  noted  here  were  made  between  plants 
in  the  same  kind  of  soil  and  with  practically  the  same  soil-moisture  con- 
ditions. Two  lots  were  grown  during  the  winter  of  1913-14  and  two  dur- 
ing the  following  summer.  During  the  winter,  one  lot  was  kept  in  a  warm 
house  at  temperatures  varying  from  about  18°  to  26°  C,  and  one  was 
kept  in  a  cool  house  at  temperatures  varying  normally  from  about  7°  to 
15°  C.  but  during  a  part  of  the  test  dropping  at  night  to  l°or  2°  C.  Both 
lots  were  exposed  to  the  full  winter  sunlight  of  the  houses.  During  the 
sunmier  test,  one  lot  was  kept  as  cool  as  possible  by  partial  shading  and 
free  ventilation,  the  temperatures  ranging  from  about  15°  to  40°  G.  but 
occasionally  exceeding  these  limits,  and  the  other  lot  was  kept  in  an 
unshaded  house  the  ventilators  of  which  were  never  opened.  The  night 
temperatures  of  the  closed  house  averaged  not  more  than  one  degree 
higher  than  those  of  the  open  house,  but  the  maximum  day  tempera- 
tures in  the  closed  house  varied  usually  from  about  44°  to  50°  G.  and  on 
three  consecutive  days  reached  55°  G.  This  extreme  heat  killed  most 
of  the  plants  grown  in  rich  soil  but  did  not  seriously  injure  those  in  poor 
soil.  Of  course  the  relative  humidity,  as  well  as  the  intensity  of  the 
light,  was  materially  different  for  the  closed  and  the  open  house. 

As  a  result  of  these  tests,  no  final  differences  in  the  development  of 
color  in  any  of  the  color  types  were  observed  between  the  lots  grown 
at  the  very  diverse  temperatures.  Of  course  differences  were  observed 
at  certain  times,  but  they  are  readily  accounted  for  by  the  facts  that  the 


Plant  Colors  ix  IMaize  21 

plants  developed  less  rapidly  at  both  excessively  high  and  excessively 
low  temperatures  than  at  more  moderate  temperatures,  and  that  color 
shows  less  during  the  early  stages  of  development  than  during  later  stages. 
It  may  be  safely  concluded,  therefore,  that  color  development  in  maize 
is  not  notably  influenced,  except  perhaps  indirectly,  by  diverse  temper- 
atures. 

SOIL   FERTILITY   AND    COLOR   DEVELOPMENT 

There  is  still  another  way  in  which  it  was  thought  the  excess  of  water 
might  indirectly  affect  the  development  of  color  in  maize  plants  in  flooded 
fields.  Not  only  may  nutrient  salts  be  removed  in  part  by  an  excess  of 
water,  but  certain  of  these  salts  —  nitrates  —  are  not  fomied  normail}^ 
in  very  wet  soils.  Tests  were  made,  therefore,  of  the  relation  of  soil 
fertihty  to  color  development. 

Rich  compared  with  poor  soil 

The  same  plant-color  types  as  were  employed  in  the  soil-moisture  and 
temperature  tests  were  included  in  these  soil-fertility  tests.  In  fact,  for  one 
of  the  tests  the  same  plants  were  used  as  in  the  moisture  and  temperature 
studies.  One  lot  of  plants  was  grown  in  rich  soil  and  a  duplicate  lot  in 
poor  soil.  Field  soil  furnished  the  basis  of  both  soils.  To  one  lot  was 
added  about  50  per  cent  by  measure  of  thoroly  decayed  stable  manure, 
and  to  the  other  about  50  per  cent  of  clean  sand. 

The  effect  of  soil  fertility  on  color  development  of  certain  color  types 
was  strikingly  apparent  from  the  time  the  seedlings  were  two  or  three 
weeks  old.  At  this  age  and  for  some  time  later,  there  was  no  appreciable 
difference  in  color  between  purples,  sun  reds,  dilute  purples,  and  dilute 
sun  reds.  In  the  rich  soil  all  these  color  tjqjes  had  very  little  red  color. 
There  was  some  color  in  the  coleoptile  and  the  lower  leaf  sheath,  but  none 
in  the  leaf  blades  except  for  a  slight  amount  in  their  margins.  The  same 
color  types  in  poor  soil  had  considerable  color  in  the  leaf  blades  and  much 
color  in  the  leaf  sheaths.  The  plants  in  rich  soil  grew  rapidly  and  were 
dark  green,  even  the  lower  leaves  remaining  healthy.  The  plants  in  i)oor 
soil,  on  the  contrary,  grew  less  rapidly  and  were  lighter  green,  and  their 
lower  leaves  soon  became  yellow  and  died.  In  all  cases  the  leaf  blades 
became  brilliantly  red  before  they  died.  This  is  in  strong  contrast  with 
the  condition  of  the  lower  leaves  of  plants  m  diy,  rich  soil.     When  the 


22  R-  A.  Emerson 

death  of  the  lower  leaves  is  caused  by  drouth,  there  is  no  corresponding 
development  of  red  color. 

At  the  age  of  six  weeks,  the  plants  in  rich  soil  were  beginning  to  show 
slightly  the  color  differences  that  in  later  stages  are  characteristic  of 
purples,  sun  reds,  dilute  purples,  and  dilute  sun  reds.  In  poor  soil,  on 
the  contrary,  no  color  differences  were  seen.  All  the  four  types  were 
highly  colored  thruout  except  for  the  youngest  leaves  (Plate  IX,  1  and  2). 

At  the  flowering  period,  the  plants  in  rich  soil  exhibited  all  the 
peculiarities  of  color  by  which  purples,  sun  reds,  dilute  purples,  and  dilute 
sun  reds  are  normally  differentiated.  Even  in  the  poor  soil  something 
of  the  same  color  differences  were  discernible  between  the  purples  and 
sun  reds  on  the  one  hand  and  the  dilute  purples  and  dilute  sun  reds  on 
the  other,  but  it  is  doubtful  whether  these  two  groups  could  have  been 
separated  accurately  from  a  mixed  culture.  It  would  have  been  very 
difficult  also  to  separate  with  certainty  the  purples  from  the  sun  reds 
or  the  dilute  purples  from  the  dilute  sun  reds,  except  by  differences  in 
anther  color  and  by  an  examination  of  the  inner  husks  and  other  parts 
protected  from  sunlight.  Differences  between  the  plants  in  rich  and  in 
poor  soil  were  still  pronounced  in  the  case  of  dilute  purples  and  dilute 
sun  reds,  but  were  scarcely  discernible  in  the  case  of  purples  and  sun  reds 
except  that  the  leaf  blades  were  somewhat  more  highly  colored  with  poor 
than  with  rich  soil  and  that  thruout  the  plants  the  colors  appeared 
brighter  in  the  former  case  owing  to  the  less  intense  green  of  the  poor- 
soil  lots. 

The  seedUngs  of  both  brown  and  green  color  types  showed  no  brown 
nor  red  color  in  either  the  rich  or  the  poor  soil.  At  the  age  of  two  months, 
some  brown  pigment  began  to  show  in  the  lower  sheaths  of  the  brown 
type,  and  at  the  flowering  stage  the  plants  had  the  typical  coloration  of 
brown  plants.  The  difference  in  the  development  of  brown  between  rich 
and  poor  soil  was  at  no  tune  very  noticeable.  The  color  showed  perhaps 
slightly  earlier,  and  was  perhaps  slightly  more  intense,  with  the  poor 
soil.  Even  this  apparent  difference,  however,  may  have  been  due  merely 
to  the  fact  that  the  plants  in  poor  soil  were  fighter  and  more  yellowish 
green  than  those  in  rich  soil.  Dark  green  might  readily  mask  the  brown 
color  somewhat.  Green  plants  of  both  type  Vic  and  type  IVg  exhibited 
no  red  nor  brown  color  at  any  stage  of  development  in  either  rich  soil 
or  poor  soil. 


Plant  Colors  in  Maize  23 

From  these  observations  it  is  apparent  that  variations  in  soil  fertihty 
may  effectively  obscure  genetic  differences.  A  knowledge  of  the  influence 
of  soil  fertility  on  color  development  is  therefore  essential  to  careful  genetic 
work  with  the  plant  colors  of  maize.  IMoreover,  since  soil  fertility  is 
subject  to  control  thru  cultural  methods,  different  degrees  of  fertility 
can.  be  used  as  an  aid  to  the  sharp  differentiation  of  certain  genetic  types. 
If,  for  instance,  it  is  desired  to  separate,  in  the  seedling  stage,  greens 
and  browns  on  the  one  hand  from  the  red-purple  series  on  the  other, 
this  can  he  accomplished  most  readily  in  poor  soil.  In  fact,  the  writer's 
practice,  in  studies  requiring  this  separation,  is  to  grow  the  seedlings  in 
pure  sand.  In  this  medium  seedlings  of  the  purple-red  series  of  color  types 
become  highly  colored  at  a  very  early  age,  while  seedUngs  of  the  green 
and  brown  types  show  absolutely  no  red  color.  If,  however,  it  is  desired 
to  distinguish  sharply  between  purple  and  dilute  puiple  or  between  sun 
red  and  dilute  sun  red,  fairly  fertile  soil  is  essential,  and,  usually,  the 
more  fertile  it  is,  the  more  easily  can  the  separation  be  made.  The  stronger 
colors  develop  almost  as  well  in  rich  as  in  poor  soil,  while  the  weaker 
colors  develop  much  less  intensely  in  rich  soils  than  in  poor  ones.  On 
very  poor  soils,  it  is  difficult  to  separate  sun  reds  from  dilute  sun  reds, 
and  almost  if  not  quite  impossible  to  distinguish  with  certainty  between 
sun  reds  and  weak  sun  reds  or  between  weak  sun  reds  and  dilute  sun  reds. 

Lack  of  particular  ivdrient  elements 

It  having  been  established  that  differences  in  soil  fertility  result  in  marked 
differences  in  the  development  of  red  color  in  maize  plants,  it  seemed 
important  to  determine  whether  particular  nutrient  salts  are  more  con- 
cerned than  others.  Accordingly,  plants  of  all  the  color  types  included 
in  the  tests  previously  reported  were  grown  in  glazed  earthen  jars  in 
clean  quartz  sand  and  watered  with  nutrient  solutions.  The  quartz 
sand  was  obtained  from  the  Department  of  Agronomy  of  the  University 
of  Nebraska,  and  was  known  to  be  practically  free  from  nutrient  elements 
except  iron.  The  nutrient  salts  and  distilled  water  were  obtained  from 
the  Department  of  Agricultural  Chemistry  of  the  same  institution.  The 
nutrient  solution  employed  was  one  that  had  given  good  results  with  maize 
in  certain  experiments  conducted  previously  by  the  Department  of 
Agronomy.  The  complete  nutrient  solution,  0.2  j^er  cent  strength, 
contained  per  liter  of  water  the  following  salts:  1  gram  Ca  (N03)2,  0.25 


24  R.  A.  Emerson 

gram  KNO3,  0.25  gram  K2HPO4,.  0.25  gram  MgS04,  and  0.25  gram  NaCl. 
Other  solutions  of  approximately  equivalent  molecular  strength,  but  each 
lacking  one  of  the  nutrient  elements  of  the  complete  solution,  were  used. 
In  the  nitrogen-free  solution,  0.7  gram  CaCl2  and  0.22  gram  K2SO4  were 
substituted  for  Ca(N03)2  and  KNO3,  respectively;  in  the  phosphorus-free 
solution,  0.25  gram  K2SO4  for  K2HPO4;  in  the  potassium-free  solution, 
0.2  gram  NaNOs  and  0.2  gram  Na2HP04  for  KNO3  and  K2HPO4, 
respectively;  in  the  calcium-free  solution,  1  gram  NaNOs  for  Ca(N03)2; 
in  the  magnesium-free  solution,  0.3  gram  Na2S04  for  MgS04;  and  in  the 
sulfur-free  solution,  0.2  gram  MgCl2  for  MgS04.  A  complete  nutrient 
solution  of  four  times  the  strength  indicated  above,  0.8  per  cent,  was 
also  used,  and  one  lot  was  given  water  without  the  addition  of  nutrients. 
After  the  first  three  weeks,  the  nutrient  solutions  were  all  used  at  double 
strength,  0.4  and  1.6  per  cent,  and  clear  water  was  occasionally  given. 
This  treatment,  owing  to  considerable  evaporation  of  water,  doubtless 
resulted  in  a  gradual  increase  in  the  strength  of  the  solutions.  The  tests 
were  carried  on  at  the  same  time  with  one  of  the  tests  of  rich  and  poor 
soil,  so  that  the  latter  might  serve  as  a  check  on  the  nutrient-solution  tests. 

At  first  the  seedlings  given  0.2-per-cent  complete  nutrient  solution 
reacted  about  as  did  those  in  poor  soil,  while  those  given  0.8-per-cent 
nutrient  solution  were  no  more  highly  colored  than  those  in  rich  soil. 
At  one  month  of  age,  the  plants  watered  for  three  weeks  with  0.2-per-cent 
and  one  week  with  0.4-per-cent  complete  solution  were  growing  rapidly 
and  were  no  more  highly  colored  than  those  in  rich  soil,  while  the  plants 
in  the  very  strong  solutions  (0.8  and  1.6  per  cent)  were  begimiing  to 
wilt,  perhaps  from  the  toxic  effect  of  the  solutions.  Thruout  the  remainder 
of  the  test,  the  plants  given  0.4-per  cent  solution,  alternated  occasionally 
with  clear  water,  were  practically  like  those  growing  in  rich  soil  both  as 
respects  vigor  of  growth  and  color  development. 

In  striking  contrast  to  the  plants  given  complete  nutrient  solution 
were  the  ones  given  clear  water  and  those  in  nitrogen-free  nutrient  solution. 
Both  these  lots  showed  much  color  even  at  two  weeks  after  germination, 
and  soon  thereafter  the  seedlings  were  red  to  the  tips  of  their  leaves. 
At  the  age  of  six  weeks  the  plants  of  these  two  lots  were  much  shorter 
and  slenderer  than  those  given  complete  nutrient  solution.  Their  upper 
leaves  were  pale  yellowish  green,  with  much  red,  and  the  lower  leaves 
were  dead  but  still  showing  the  red  color  that  had  developed  earlier. 


Plant  Colors  in  Maize  25 

Next  in  point  of  coloration  to  the  seedlings  given  nitrogen-froe  nutrient 
solution  and  those  given  water  alone,  were  the  ones  grown  in  phosphorus- 
free  nutrient  solution.  The  latter  did  not  show  red  color  so  quickly  as 
did  the  nitrogen-free  lot,  and  at  no  time  did  they  develop  quite  so  much 
color.  They  showed,  however,  considerably  more  color  at  the  age  of  one 
month  than  did  seedlings  in  the  complete  nutrient  solution.  When  six 
weeks  old  the  plants  of  the  phosphorus-free  lot  were  relatively  small, 
and  had  pale  green  upper  leaves  with  little  red  color  and  dead  lower 
leaves  which  still  retained  much  red  pigment.  While  somewhat  larger 
than  the  plants  in  nitrogen-free  solution  and  those  in  clear  water,  the 
phosphorus-free  lot  began  wilting  when  about  six  weeks  old  and  died 
considerably  in  advance  of  the  nitrogen-free  lot.  Their  roots  showed 
early  indications  of  injury,  perhaps  from  toxic  effects  of  the  solution. 

Plants  of  all  the  other  lots,  in  which  one  or  another  nutrient  element 
had  been  omitted  from  the  solution,  exhibited  little  or  no  color  reaction 
to  the  lack  of  a  particular  element.  All  of  them  were  more  vigorous 
in  growth  than  the  nitrogen-free  and  phosphorus-free  lots,  but  much  less 
so  than  the  lot  given  complete  nutrient  solution.  The  sulfur-free  lot 
for  a  time  seemed  to  be  developing  more  red,  but  later  showed  perhaps 
even  less  red,  than  the  lot  with  complete  nutrient  solution.  The  mag- 
nesium-free lot  showed  prominent  dark  and  light  green  stripes  in  the 
leaves  similar  to  the  green-striped  chlorophyll  pattern  (Lindstrom,  1918). 
In  some  cases  the  tissue  of  the  lighter  stripes  died  and  there  was  often 
some  red  coloration  next  to  the  dead  tissue.  The  potassium-free  lot  had 
about  the  same  amount  of  red  color  as  the  lot  given  complete  nutrient 
solution,  while  the  calcium-free  lot  showed  less  red  color  than  any  other 
lot  in  the  test. 

It  is  perhaps  noteworthy  that  in  the  nitrogen-free  lot,  and  to  some 
extent  in  the  phosphorus-free  lot.  the  new  growth  seemed  to  take  place 
at  the  expense  of  the  older  leaves.  The  lower  leaves  first  became  light 
or  yellowish  green,  then  red,  and  finally  died.  That  the  development  of 
red  pigment  is  not  necessarily  connected,  however,  with  the  breaking 
down  of  the  protoplasm,  is  seen  in  the  failure  of  seedlings  to  develop 
red  color  in  the  older  dying  leaves  of  the  lot  in  complete  nutrient  solution 
and  of  the  potassium-free,  magnesium-free,  and  calcium-free  lots.  In  the 
calcium-free  lot,  growth  was  stopped  by  the  death  of  the  youngest  parts, 
including  the  partly  unrolled  upper  leaves,  and  yet  these  parts  showed 


26  R.  A.  Emerson 

no  red.  Moreover,  the  dying  of  the  lower  leaves  due  to  excessively  dry 
soil,  or  of  the  upper  leaves  from  intense  heat,  is  not  accompanied  by  the 
development  of  red  pigment. 

In  similar  tests  with  cuttings  of  Tradescantia  viridis  and  T.  lockensis 
grown  in  distilled  water,  in  complete  nutrient  solutions,  and  in  solutions 
each  lacking  one  nutrient  element,  namely,  N,  P,  K,  Ca,  Mg,  or  S, 
Czartkowski  (1914)  found  that  after  five  weeks  red  color  appeared  in 
the  newly  developed  leaves  in  the  cases  of  only  distilled  water  and  nitrogen- 
free  solutions.  He  states,  however,  that  Susuki  reported  a  similar  effect 
on  plants  of  Hordeum  from  a  lack  of  phosphorus.  It  will  be  recalled 
that  in  the  writer's  tests  with  maize,  lack  of  nitrogen  gave  the  most  pro- 
nounced effect  and  lack  of  phosphorus  induced  considerable  color  develop- 
ment, while  lack  of  sulfur  seemed  for  a  time  to  have  an  effect  but  no 
effect  was  apparent  later. 

Frorh  the  results  of  the  tests  reported  above,  it  is  apparent  that  the 
reddening  of  young  plants  in  flooded  fields,  as  well  as  the  intensification 
of  color  in  older  plants  grown  on  poorly  drained  heavy  soils,  is  not  due 
to  any  direct  effect  of  the  excess  of  water  in  the  soil  or  to  a  direct  effect 
of  the  somewhat  lower  temperatures  accompanying  such  conditions,  but 
rather,  perhaps,  to  the  lessened  fertility  of  cold,  wet  soils  or  to  inability 
of  the  plant  to  obtain  adequate  nutrients  under  such  conditions.  An 
excess  of  water  not  only  may  remove  certain  nutrient  salts  from  the  soil, 
but  also  may  prevent  or  greatly  check  nitrification.  Moreover,  under 
these  conditions  the  soil  solution  is  probably  less  concentrated.  The 
reddening  of  young  plants  in  cold,  wet  soils  in  spring,  the  greater  develop- 
ment of  color  in  plants  maturing  in  the  cool  weather  of  late  autumn,  and 
the  excessive  development  of  red  in  plants  on  very  light  sandy  soils,  are 
possibly  all  due  to  the  plants'  inability  to  get  from  such  soils  an  adequate 
supply  of  nutrient  salts,  particularly  of  nitrates. 

RELATION  OF  CARBOHYDRATES  TO  COLOR 

Several  authors,  notably  Wheldale  (1911),  have  discussed  the  relation 
of  sugars  to  the  production  of  anthocyanins  in  plants.  Knudson  (1916: 
24,  62)  found  that  maize  and  vetch  grown  in  nutrient  solutions  containing 
certain  sugars  developed  markedly  more  red  color  than  did  plants  grown 
in  sugar-free  solutions.  The  writer  has  observed  repeatedly  an  apparent 
relation  between  an  excess  of  carbohydrates  and  the  development  of  red 


Plant  Colors  in  Maize  27 

color  in  maize  leaves.  Of  course  the  relation  has  been  observed  only  in 
typos  that  normally  produce  some  rod  pigment.  Neither  brown,  type  V, 
nor  green  of  either  type  IVg  or  type  VI,  has  ever  been  observed  with  red 
color  in  the  leaves,  no  matter  what  treatment  has  been  given  the  plants. 
When  loaves  are  folded  at  right  angles  to  the  midrib  and  the  margin  of 
the  fold  is  creased  sufficiently  to  break  the  softer  tissues  but  not  enough 
to  break  the  water-conducting  vessels,  the  part  beyond  the  crease  does 
not  wilt,  but  within  a  few  days  it  begins  to  lose  some  of  its  chlorophyll 
and  within  a  week  it  becomes  highly  colored  red  (Plate  X,  1).  When  leaves 
are  similarly  treated  late  in  the  afternoon  of  a  bright  day  and  the  plants 
are  kept  in  a  dark  room  until  the  following  day,  the  starch  is,  of  course, 
found  to  have  disappeared  by  translocation  from  the  part  of  the  leaves 
below  the  crease,  while  the  cells  of  the  bundle  sheaths  of  the  part  beyond 
the  crease  are  found  to  be  packed  with  starch.  There  is  so  much  starch 
in  this  part  of  a  creased  leaf  that,  on  extraction  of  the  chlorophyll  with 
alcohol  and  treatment  with  iodin,  the  whole  end  of  the  leaf  becomes 
almost  black.  While  this  does  not  prove  a  direct  relation  between  an 
excess  of  carbohydrates  and  the  development  of  red  pigment,  taken  in 
connection  with  all  the  other  observations  it  strongly  suggests  such  a 
relation. 

It  has  been  observed  repeatedly  that  sweet-corn  plants  from  which 
the  ears  have  been  removed  in  the  edible  stage  develop  within  a  week 
or  two  much  more  color  than  do  neighboring  plants  that  still  retain  their 
ears.  Barren  stalks  also  frequently  show  more  color  than  do  their  ear- 
bearing  neighbors.  While  no  direct  determination  of  the  matter  has  been 
made  it  seems  likely  that  barren  plants,  as  well  as  plants  from  which  the 
immature  ears  have  been  removed,  may  carry,  in  their  leaves,  husks, 
and  cuhns,  an  excess  of  carbohydrates  which  would  normally  have  been 
deposited  in  the  developing  seeds. 

The  strong  development  of  red  pigment  in  the  white,  chlorophyll-free 
stripes  of  the  japonica-striped  type,  when  leaves  are  creased  or  when 
plants  are  grown  in  poor  soil,  may  well  be  due  to  the  passage  of  sugars 
from  the  green  to  the  white  parts.  In  some  instances  the  red  color  seems 
to  develop  more  quickly  in  the  white  stripes  than  in  the  green  (Plate  X,  2). 
Whether  this  difference  is  a  real  one,  due  perhaps  to  the  readier  access 
of  light  to  the  white  parts,  or  is  only  an  apparent  difference  due  to  the 


28  R.  A.  Emerson 

masking  effect  of  the  green  color,  is  not  known.     Certainly  red  pigments 
develop  first  in  the  chlorophyll-free  epidermal  cells.^ 

Czartkowski  (1914)  suggested,  in  connection  with  the  account  of  his 
study  of  the  relation  of  nutrient  elements  to  color  development,  that 
lack  of  nitrogen  may  check  protein  synthesis,  thus  leaving  unused  the 
carbohydrates  that  would  otherwise  be  used  in  growth,  and  that  the 
excess  of  carbohydrates  may  favor  anthocyanin  formation.  He  was 
unable  to  understand  why  a  lack  of  phosphorus  or  of  sulfur  did  not  like- 
wise influence  color  development,  since  these  elements  also  are  necessary 
to  protein  synthesis.  Lack  of  phosphorus  does  apparently  bear  some 
relation  to  color  development  in  maize,  but  the  v/riter's  tests  afforded 
little  or  no  evidence  of  such  a  relation  between  a  lack  of  sulfur  and  pigment 
formation.  If  lack  of  nitrogen  induces  anthocyanin  formation  thru  the 
checking  of  growth,  thus  allowing  an  accumulation  of  carbohydrates,  it 
is  not  clear  why  other  means  of  checking  growth,  such,  for  instance,  as 
dry  soil,  do  not  also  favor  pigment  formation,  unless  these  other  growth- 
checking  factors  at  the  same  time  limit  photosynthetic  activity.  It  is 
of  interest  to  recall  in  this  connection  that  plant  colors  of  maize  —  brown 
no  less  than  the  red-purple  series  —  develop  first  in  the  older  parts  where 
growth  first  ceases,  such  as  the  lower  sheaths  and  the  upper  parts  of  the 
internodes  of  the  culm. 

SUMMARY 

Whatever  is  the  final  outcome  of  studies  of  the  relation  of  environmental 
factors  to  plant-color  development  in  maize,  enough  has  been  noted  to 
indicate  a  very  complex  relation.  What  is  more  complex  than  this  chain 
of  events  —  a  chain  that  lacks  many  links  in  the  way  of  particular  chemical 
reactions:  cold,  wet  soil  checks  or  inhibits  nitrification;  lack  of  nitrogen 
in  available  fonn  limits  protein  synthesis,  which  in  turn  allows  an  accumu- 
lation of  carbohydrates;  an  excess  of  carbohydrates  favors  anthocyanin 
formation.  The  result  is  that  young  maize  plants  in  cold,  wet  soil 
become  highly  colored.  But  to  all  this  must  be  added  the  factor  of 
sunlight,  without  which  no  red  color  develops  in  the  leaves  of  young 
plants.  And  not  the  least  consideration  is  the  important  fact  that  only 
plants  of  certain  genetic  constitutions  show  this  color  reaction  to  wet 
soils.     It  is  to  be  hoped  that  some  day,  thru  the  coordinated  efforts  of 

2  The  histology  of  color  development  of  the  several  plant-color  tvpes  has  been  investigated  by  Dr.  E.  G. 
Anderson,  but  the  observations  have  not  been  published.^" 


Plant  Colors  in  Maize  29 

biochemists,  physiologists,  and  geneticists,  it  may  be  possible  to  reach 
conclusions  in  this  field  of  quite  as  fundamental  importance  to  biology 
as  the  recent  results  of  similar  efforts  of  cytologists  and  geneticists. 

GENETIC  ANALYSIS  OF  COLOR  TYPES 

In  the  preceding  parts  of  this  paper  the  several  plant-color  types  of 
maize  are  described  and  the  variations  induced  in  them  l)y  diversities 
of  environment  are  discussed.  The  remainder  of  the  paper  is  devoted  to 
a  presentation  of  data  of  a  more  distinctly  genetic  nature,  and  to  an 
attempt  at  a  factorial  analysis  of  these  data. 

The  data  are  presented  as  if  the  F2  generation  of  the  more  complex 
crosses  were  the  first  which  were  obtained  and  on  which  hypotheses  were 
formulated  and  appropriate  tests  made.  As  a  matter  of  fact,  this  was 
not  in  all  cases  the  actual  procedure.  In  several  instances  the  results  of 
some  of  the  simpler  crosses  were  at  hand  and  were  used  as  an  aid  to  the 
interpretation  of  the  more  complex  ones  when  the  latter  were  obtained. 
Moreover,  the  hypothesis  presented  here  was  not  the  only  one,  nor  indeed 
the  first  one,  formulated.  As  is  usual  in  such  work,  various  hypotheses 
were  devised,  tested,  and  discarded,  until  finally  a  factorial  interpretation 
was  found  that  fitted  fairly  well  all  the  facts  known.  Many  results  with 
a  bearing  on  plant  color  were  obtained  in  other  studies  extending  over 
a  period  of  some  eight  or  nine  years.  Since  the  practice  of  the  writer 
is  to  number  his  pedigrees  consecutively  from  year  to  year,  an  inspection 
of  the  pedigree  numbers,  as  listed  in  the  tables,  suggests  at  once  that  some 
of  the  data  presented  as  checks  on  other  results  could  not  have  been 
obtained  after  these  other  results.  Any  data  applicable  as  a  test  have 
been  so  used  whether  obtained  for  that  purpose  or  in  connection  with  other 
studies.  Whether  this  mode  of  presentation  is  the  best  one  must  be 
left  to  the  judgment  of  others.  This  at  any  rate  is  certain:  the  data  could 
not  have  been  presented  chronologically  and  discussed  in  relation  to  such 
hypotheses  as  happened  to  be  under  test  at  the  time  any  particular  results 
were  obtained,  without  adding  unnecessarily  to  the  complexity  of  the  paper. 

CROSSES   INVOLVING    THE    FACTOR   PAIRS   A  a,   B  b,    PI  pi 

Purple  la  x  green  Vic 

Generations  Fi  and  F^. —  When  purple  plants  with  purple  anthers 
(type'  la)    are   crossed  with   plants   lacking   all   red,    purple,    or   brown 


30  R.  A.  Emerson 

pigment,  commonly  known  as  green  (type  Vic),  the  Fi  offspring  are  full 
purple.  Whether  or  not  a  quantitative  determination  of  purple  pigment 
might  reveal  a  difference,  no  dilution  of  the  purple  color  is  apparent  to 
the  eye  in  the  Fi  plants.  Four  crosses  of  this  sort  with  a  total  Fi  progeny 
of  111  purple  plants  are  listed  in  table  1  (appendix,  page  121). 

Seven  Fo  progenies  of  the  Fi  plants  recorded  in  table  1  are  hsted  in 
group  1  of  table  2.  Fourteen  other  similar  F2  progenies  are  shown  in 
group  2  of  the  same  table.  The  Fi  plants  from  which  these  fourteen  F2 
progenies  came  are  not  recorded  in  table  1  because  their  purple  parents 
were  not  homozygous.  Some  of  the  purple  plants  used  as  parents  in 
these  crosses  were  Fi's  of  the  original  cross  of  purple  with  green.  Others 
were  from  Fi  or  some  later  generation  of  other  crosses  having  the  purple 
type  as  one  parent.  In  every  case  the  other  parent  was  a  green  plant 
of  type  Vic.  Since  the  purple  Fi  plants  of  these  crosses  were  presumably 
the  same  genotypically  as  the  Fi's  shown  in  table  1,  their  F2  progenies  may 
well  be  included  tentatively  with  those  of  group  1  of  table  2.  Each  of  the 
twenty-one  F2  lots  exhibited  six  distinct  classes  of  plants  with  respect  to 
color.    The  2117  plants  were  distributed  among  the  six  classes  as  follows: 

Purple       ®",^  ^^^^^e  Dilute       g  ^  ^    ^ 

^  red  purple  sun  red 

952  305  275  91  278  216  2,117 

Obviously  no  simple  3 : 1  mendelian  behavior  is  in  evidence  here.  More- 
over, only  four  classes  are  expected  in  dihybrids  where  dominance  is 
exhibited.  With  dominance  trihybrids  ordinarily  give  eight  classes  in  F2 
in  the  well-known  numerical  relation  of  27:9:9:3:9:3:3:1,  while  only 
six  classes  were  observed.  Inspection  of  the  distribution  of  the  2117 
individuals  given  above,  however,  suggests  the  possibility  of  a  27:9:9: 
3:9:7  relation,  which  should  be  realized  in  a  trihybrid  if  the  last  three 
classes  were  indistinguishable.  A  comparison  of  observed  numbers  with 
those  expected  on  this  hypothesis  follows: 

Color  types         Purple     ^un     ™u}:   ™>i^.  Brown   Green     Total 

"Observed 952        305         275  91         278         216       2,117 

Calculated^ 893        298        298  99        298        232      2,118 

Difference -j-59        +7      —23        —8      —20      —16  —1 

3  In  this  and  most  of  the  following  comparisons,  the  theoretical  distributions  are  calculated  to  the  nearest 
whole  number. 


Plant  Colors  m  Maize  31 

There  are  rather  large  differences  between  observed  and  expected 
numbers.  The  purples  are  considerably,  and  the  sun  reds  slightly,  in 
excess  of  expectation,  while  each  of  the  other  four  classes  has  too  few 
individuals.  The  probability  that  these  deviations  may  be  due  to  chance 
is  approximately  0.11.  One  might  expect,  therefore,  to  encounter  chance 
deviations  of  the  magnitude  observed  here  about  once  in  nine  such  trials. 
This,  of  course,  does  not  substantiate  the  three-factor  hypothesis,  but 
merely  indicates  that  it  is  not  necessarily  out  of  keeping  with  the  ol)servetl 
facts. 

Backcrosses  with  green  Vic. —  A  better  criterion  perhaps  is  afforded  by 
the  backcross  of  Fi  purples  with  the  green  parent  type.  Records  of  such 
crosses  are  shown  in  table  3.  The  backcrosses  with  F/s  of  table  1  are 
listed  in  group  1,  and  backcrosses  with  similar  Fi  purples  of  other  lots 
in  group  2.  The  same  six  phenotypcs  o])served  in  the  regular  Fo  generation 
occurred  here  also.  On  the  basis  of  the  three-factor  hypothesis  and  with 
the  assumption  that  there  are  three  sorts  of  greens  indistinguishable  from 
one  another,  the  individuals  of  this  backcross  should  be  distril^utcd  equally 
to  five  classes  with  the  sixth  class  containing  three  times  as  many  indi- 
viduals as  any  other  class.  The  observed  distribution  of  the  1317  indi- 
viduals of  the  fourteen  progenies  is  here  compared  with   the  expected 

distribution: 

^  ,      ,  T^       1       Sun      Dilute   Dilute    -o  r<  t.  x  i 

Color  types  Purple     ^.^^j       purple  sun  red  ^^'°^^    ^'»'^^"     Total 

Observed 170         160         176         160         172        479       1,317 

Calculated 165         165         165         165         165        495       1,320 

Difference +5        — 5       +11        — 5        +7      ■ — 16  ■ — 3 

While  a  few  of  the  backcross  progenies  listed  in  table  3  exhibit  con- 
siderable deviations  from  the  expected  distribution,  the  fourteen  lots 
taken  together  approximate  it  closely.  The  probal:)ility  that  the  observed 
deviations  may  be  due  to  chance  in  random  sampling  is  about  0.85. 
Deviations  as  great  as  these  are  to  be  expected  thru  chance  alone,  there- 
fore, in  about  six  out  of  seven  trials. 

Workiiig  hypothesis. —  To  the  three  factor  pairs  used  to  interpret  the 
results  here  reported,  the  symbols  A  a,  B  h,  and  PI  pi  have  been  assigned. 
The  gene  A  is  an  anthocyanin  factor.  In  the  presence  of  a  a  ordinarily 
no  anthocyanic  pigment  develops,  tho  brownish,  or  flavonol  (Sando  and 
Bartlett,  1921),  pigment  may  be  formed.  The  pair  Bb  is  named  for  its 
2 


32  R.  A.  Emerson 

connection  with  the  development  of  brown  pigment,  tho  when  both  A  and 
B  are  present,  sun  red  pigment  is  produced.  The  pair  PI  pi  is  so  teraied 
because  of  its  relation  to  purple  pigment.  The  phenotypic  formulae  as- 
signed to  the  several  classes  of  plant  color  under  consideration  here  are 

as  follows: 

ABPl —     la,  purple 

AB  pi  —  Ila,  sun  red 

Ah  PI  — Ilia,  dilute  purple 

A  b  pi  —  IVa,  dilute  sun  red 

aBPl—   V,     brown 

aBpl  —Via] 

ah  PI  —  VIb  !•  green 

ah  pi    —  VIcJ 

Obviously  the  hypothesis  in  accordance  with  which  the  above  factorial 
assignments  have  been  made  is  subject  to  several  genetic  tests.  Naturally 
the  first  tests  to  suggest  themselves  are  studies  of  the  behavior  of  the 
several  F2  types  in  F3  and  later  generations.  Next  in  order  are  inter- 
crosses between  the  several  classes.  For  reasons  that  will  appear  shortly, 
one  of  these  intercrosses  is  here  dealt  with  before  consideration  is  given 
to  F3  generations  from  the  several  F2  classes. 

Dilute  sun  red  IVa  x  brown  V 

From  an  examination  of  the  factorial  assignments  listed  above,  it  is 
evident  that  crosses  of  dilute  sun  red,  A  h  pi,  with  brown,  a  B  PI,  should 
produce  purple  Fi  plants,  A  B  PI.  Moreover,  these  Fi  purples  should  be 
heterozygous  for  all  three  factors,  AaBh  PI  pi,  just  as  was  assumed  for 
the  original  cross  of  purple,  A  B  PI,  with  green,  a  h  pi.  The  F2  and  later 
behavior  of  this  cross  should  also,  barring  linkage,  be  hke  that  of  the  original 
cross,  so  that  the  two  can  most  conveniently  be  considered  together. 

Generations  Fi  and  Fo. —  The  Fi  generation  of  twenty-six  crosses  of 
dilute  sun  red  with  brown  plants  is  given  in  table  4  (page  123).  The  dilute 
sun  red  parent  plants  were  chosen  from  any  convenient  lots  known  to  be 
homozygous  with  respect  to  ^,  b,  and  pi.  The  brown  parent  plants,  on 
the  other  hand,  were  from  the  F2  and  later  generations  of  the  original 
cross  of  purple  and  green  or  from  other  crosses.  It  was  to  be  expected, 
therefore,  that  some  of  the  biown  plants  would  be  homozygous  for  both 
B  and  PI,  and  some  would  be  heterozygous  for  B,  some  for  Pi,  and  some 


Plant  Colors  in  Maize  33 

for  both  B  and  PI.  This  expectation  was  fully  reaUzed.  In  group  1  of 
table  4  are  recorded  the  progenies  of  nine  crosses  with  a  total  of  263  indi- 
viduals. All  but  one  plant  of  the  lot  were  purple.  The  one  dilute  sun 
red  plant  was  presumably  due  to  accidental  pollination  of  the  dilute 
sun  red  mother  plant.  Since  the  dilute  sun  red  parents  of  all  these  crosses 
were  A  A  hh  pi  pi,  the  brown  parents  of  the  crosses  hsted  in  group  1  must 
presumably  have  been  aa  B  B  PI  PI.  Similarly,  the  seven  crosses  listed 
in  group  2  gave  purple  and  sun  red  plants  only,  143  of  the  former  and  147 
of  the  latter.  Evidently  the  brown  parents  of  these  crosses  were  aa  B  B 
PI  pi.  Again,  the  six  crosses  shown  in  group  3  gave  105  purple,  123 
dilute  purple,  and  no  other  plants.  The  brown  parents  of  the  crosses 
were  therefore,  presumably,  aaBh  PI  PI.  Finally,  the  four  crosses  listed 
in  group  4  gave  9  purple,  11  sun  red,  19  dilute  purple,  and  17  dilute  sun 
red.  The  brown  parents  of  these  four  crosses  are  assumed,  consequently, 
to  have  been  a  a  B  b  PI  pi.  *' 

The  F2  results  from  the  purple  Fi  plants  of  these  crosses  of  dilute  sun 
red  with  brown  are  recorded  in  table  5.  Fourteen  progenies  of  the  Fi 
plants  hsted  in  table  4  are  shown  in  group  1  of  table  5,  and  five  progenies 
from  similar  Fi  plants  not  listed  in  talkie  4  are  entered  in  group  2.  Here, 
just  as  with  the  results  of  the  cross  of  purple  with  green  (table  2),  fairly 
marked  discrepancies  between  theory  and  observation  appear  when  the 
several  progenies  are  taken  separately.  When,  however,  the  nineteen 
progenies  are  considered  together,  very  close  agreement  is  found  between 
observation  and  exjiectation,  as  is  shown  by  the  comparison  below.  The 
probabihty  that  such  deviations  as  are  observed  may  be  due  to  chance  is 
approximately  0.88,  which  means  that  only  about  once  in  eight  trials 
would  as  good  a  fit  be  expected.     The  comparison  follows: 


Color  types 

Purple 

la 

Observed 

847 

Calculated. .  .  . 

845 

DiiTerence .... 

+2 

Sim 
red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Brown 
V 

Green 
Via,  b,  c 

Total 

282 

281 

94 

267 

233 

2,004 

282 

282 

94 

282 

219 

2,004 

0—1  0        —15  +14  0 

Backcrosses  with  green  Vic. —  In  addition  to  the  F2  results  noted  above 
as  derived  from  self-poUinated  Fi  purple  plants,  a  few  F,  purples  were  back- 


34  R.  A.  Emerson 

crossed  with  the  triple  recessive  green,  type  Vic.  The  records  of  these 
crosses,  seven  in  all,  are  presented  in  table  6.  The  results  are.  as  expected, 
in  close  agreement  with  the  Imckcross  data  from  the  cross  of  purple  with 
green.  The  comparison  below  indicates  a  good  fit  of  (calculated  to  observed 
frequencies  for  the  lot  as  a  whole.  The  probability  that  such  deviations 
as  are  observed  may  be  due  to  mere  chance  is  about  0.82,  indicating  that 
as  great  departures  from  expectation  as  these  might  be  expected  about 
four  times  in  five  trials.     The  comparison  follows: 

Color  types     Purple  Sun  red  p^j.p]g  gun^red  ^^'^^^  ^'^'^^^^  Total 

la  Ila  Ilia  IVa          V  Via,  b,  e 

Observed 84  72          78  72  79  249  634 

Calculated....         79  79          79  79  79  237  632 


Difference....       +5        —7        —1  —7  0  +12  +2 

Backcrosses  of  la  x  Vic  and  IVa  x  V  with  IVa 

Purple  plants  of  Fi  of  the  crosses  purple  x  green  and  dilute  sun  red  x 
brown  were  crossed  with  homozygous  dilute  sun  red  stocks.  On  the 
basis  of  the  hypothesis  used  above,  the  Fi  plants  are  assumed  to  be  ^  a 
B  b  Plpl  and  the  dilute  sun  red  plants  A  A  hb  pi  pi.  Four  classes  of 
plants,  purple,  sun  red,  dilute  purple,  and  dilute  sun  red,  should  be  pro- 
duced in  equal  numbers  by  this  cross.  The  data  are  presented  in  table  7 
(page  125).  Progenies  of  Fi  plants  from  the  cross  purple  x  green  are  listed 
in  group  1  and  those  from  the  cross  dilute  sun  red  x  brown  in  group  2. 
As  will  be  seen  from  the  comparison  below,  the  observed  numbers  are  in 
fair  agreement  with  the  hypothesis.  The  probability  that  such  deviations 
as  occur  may  be  due  to  chance  is  approximately  0.67.  In  other  words, 
there  are  two  chances  in  three  that  deviations  of  this  sort  are  due  to 
errors  of  random  sampling  alone.     The  comparison  follows: 

Color  types  Purple       Sun  red  ,  ,      Total 

^^  ^  purple       sun  red 

la  Ila  Ilia  IVa 

Observed 299  270  288  291  1 ,148 

Calculated 287  287  287  287  1  ,148 


Difference +12  —17  +1  +4  0 


Plant  Colors  in  Maize 


35 


Behavior  of  Fz  color  types  in  later  generations 

From  all  the  foregoing  it  appears  that  the  results  obtained  are  in  close 
accord  with  the  proposed  three-factor  hypothesis  in  the  case  of  both 
the  cross  purple  x  green  and  the  cross  dilute  sun  red  x  brown,  and  not 
alone  for  the  Fi  and  Fo  generations  but  also  for  l)ackcrosses  with  green 
and  with,  dilute  sun  red.  It  is  now  in  order  to  inquire  into  the  behavior 
of  these  crosses  in  F.-s  and  later  generations.  In  the  presentation  of  the 
additional  data,  the  two  crosses  purple  x  green  and  dilute  sun  red  x  brown 
will  be  considered  together. 

Later  behavior  of  F2  purple  la. —  Purple  plants  of  the  F2  generation  of 
the  crosses  under  consideration  are  expected  to  be  of  eight  genotypes. 
The  expected  F2  genetic  formulae  and  the  F3  color  classes,  together  with 
the  relative  numbers  of  each,  are  as  follows: 


F3  color 

types 

F2  genotypes 

Purple 
la 

Smi  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Brown 

Green 
VI 

\-~  A  AB  B  PlPl 

1 
3 
3 
3 
9 
9 
9 
27 

1 

3 

3 

9 

I 
3 

3 

9 

i 

3 

I 

3 

3 
9 

2  — A  ABB  PI  pi 

2  — A  A  Bb  PI  PI 

2  —  AaBBPlPl 

4  — A  A  Bb  PI  pi 

A  —  AaBB  Plpl 

1 

A  — A  a  Bb  PI  PI 

1 

8  — A  a  Bb  PI  pi 

7 

If,  instead  of  being  selfed,  the  F2  purple  plants  are  backcrossed  to 
green  of  type  Vic,  the  same  F3  color  classes  are  expected  but  the  several 
classes  should,  of  course,  be  equally  frequent  except  in  case  of  the  F2 
triple  heterozygotes,  which  should  thi'ow  three  times  as  many  greens  as 
of  each  of  the  other  five  types. 

The  F3  data  from  thirty-five  F2  plants  are  recorded  in  table  8  (page  125). 
In  group  1  of  the  table  are  listed  the  progenies  of  eight  selfed  and  one 
backcrossed  F2  plants.  From  the  backcross  six  color  types  appeared 
in  frequencies  of  4:4:11:4:4:18.     The   theoretical  number  for  the  first 


36  R.  A.  Emerson 

five  classes  is  5.6  and  for  the  sixth  class  is  17.  The  probability  that  such 
deviations  as  occur  are  due  to  chance  is  approximately  0.35,  or  more 
than  one  in  three.  The  eight  self-polHnated  plants  gave  together  the  six 
types  in  frequencies  as  follows: 

Color  types      Purple  Sun  red  J^J|.^|^  ^^jjf^^^  Brown  Green  Total 

la          Ila        Ilia      IVa           V  Via,  b,  c 

Observed 193          66          60           16          57  34  426 

Calculated 180          60          60          20          60  46  426 

Difference +13+6  0—4—3  —12  0 

The  probability  that  such  deviations  as  occur  may  be  due  to  errors 
of  random  sampling  is  practically  0.27.  Similar  deviations  might  there- 
fore be  expected  somewhat  more  than  once  in  four  trials.  It  will  be 
noted  that  two  progenies  lacking  class  IV  are  included  in  this  lot  (group  1, 
table  8).  The  total  number  of  plants  in  these  progenies  were  37  and 
17,  respectively,  and  they  should  therefore  have  had,  respectively,  two 
and  one  plants  in  class  IV. 

Five  Fo  purple  plants  (group  2,  table  8)  gave  four  color  types  (la,  Ila, 
Ilia,  and  IVa)  in  F^,  with  total  frequencies  as  shown  below.  Here  the 
probability,  P,  equals  0.75,  indicating  that  deviations  of  this  magnitude 
might  be  expected  thru  chance  in  three  out  of  four  trials.  The  com- 
parison of  observed  with  theoretical  distributions  follows: 

Color  types  Purple      Sun  red      ^'^^^^      ^^^^^*^.  Total 

"^^  ^  purple      sun  red 

la  Ila  Ilia  IVa 

Observed 102  36  29  13  180 

Calculated 101  34  34  11  180 

Difference +1  +2  —5  +2  0 

Progenies  of  seven  other  purple  F2  plants  (group  3,  table  8)  consisted 
cf  the  four  color  types  la,  Ila,  V,  and  Via.  Four  of  these  F2  plants  were 
self-pollinated  and  gave  a  total  of  164  F3  plants.  Four,  including  one  that 
was  also  selfed,  were  backcrossed  to  green  and  yielded  a  total  of  209  F3 
plants.  For  the  progenies  from  selfed  F2  plants  P  =  0.20,  and  for  those 
from  backcrossed  plants  P  =^  0.57.     There  is,  therefore,  one  chance  in  five 


Plant  Colors  l\  Maize 


37 


in  the  one  case  and  considerably  more  than  an  even  chance  in  the  other 

case  that  deviations  of  the  kind  noted  may  have  been  due  to  errors  of 
random  sampUng.     The  comparisons  follow: 

Color  types  Purple     Sun  red    Brown     Green        Total 

la  Ila  V  Via 

c.  ,.  J  /Observed 95            31            23            15  164 

^^^^^"^  \  Calculated 92            31            31            10  164 

Difference +3              0          —8          +5  0 

Backcrossed<;^^''^''^'^^---           54            58            44            53  209 

^^^^"^"^^''^"^^  Calculated...           52            52            52            52  208 


Difference....         +2  +6  —8  +1  +1 

Seven  self-pollinated  Ff  purple  plants  gave  progenies  consisting  of  the 
four  color  types  la,  Ilia,  V,  and  VIb  (group  4,  table  8).  Here  P  =  0.75, 
indicating  that  there  are  three  chances  in  four  that  such  deviations  as  are 
shown  are  due  to  chance.     The  comparison  follows: 

Color  types  Purple     IJjj.p|g     Brown      Green       Total 

la  Ilia  V  VIb 

Observed 318  114  111  42  585 

Calculated 329  110  110  37  586 

Difference —11  +4  +1  +5  —1 

Five  F2  purple  plants  from  self-pollination  gave  only  two  color  types 
(la  and  Ila)  in  F3  (group  5,  table  8).  The  total  number  of  F3  individuals  was 
183,  of  which  139  were  of  color  type  la  and  44  were  of  color  type  Ila, 
the  expected  numbers  being,  respectively,  137  and  46,  and  the  deviation 
equaling  2  ±  4.  One  of  these  F>  plants  was  also  backcrossed  to  two  greens, 
resulting  in  12  purple  and  9  sun  red  F3  plants  where  equality  of  the  two 
classes  was  expected.     The  deviation  here  is  1.5  ±  1.5. 

Finally,  two  self-pollinated  Fo  purple  plants  produced  217  F3  individuals 
(group  6,  table  8)  of  color  types  la  and  Ilia.     There  were   168  purple 


38  R.  A.  Emerson 

and  49  dilute  piirple  where  the  expected  numbers  were  163  and  54,  respec- 
tively —  a  deviation  of  5  ±  4.3. 

It  is  seen,  then,  that  in  every  case  the  F3  progenies  of  F2  purple  plants 
were  of  color  types  expected  on  the  basis  of  the  three-factor  hj^pothesis, 
and  that  the  F3  distributions  within  any  group  were  in  close  agreement 
with  expectation.  It  is  particularly  noteworthy,  however,  that  not  all 
types  of  F3  behavior  were  observed,  and  that  the  distribution  of  the 
progenies  of  the  thirty-five  F2  plants  tested  was  in  rather  imperfect  agree- 
ment with  expectation.  Thus,  no  Fo  purple  plant  bred  true  in  F3  where 
one  such  plant  was  expected,  and  none  gave  progenies  of  pui'ple  and 
brown  only  where  at  least  two  with  such  behavior  were  expected.  It 
has  already  been  pointed  out  (page  35)  that  eight  classes  of  behavior  of 
Fo  purples  are  looked  for,  and  that  any  twenty-seven  F2  piu'ple  plants 
should  be  distributed  with  respect  to  their  F3  behavior  in  the  relation 
1:2:2:2:4:4:4:8.  The  actual  and  theoretical  distributions  are  compared 
as  follows: 

Observed 05205  7  79  35 

Calculated.., 1.3        2.6        2.6        2.6        5.2        5.2        5.2      10.4         35.1 

Difference —1.3     +2A    —0.6     —2.6    —0.2     +1.8     +1.8    —1.4        —0.1 

Wliile  mere  inspection  of  the  above  comparison  might  suggest  poor  agree-. 
ment  between  theory  and  observation,  nevertheless  P  =  0.36,  indicat- 
ing that  such  deviations  as  occur  might  be  expected  in  more  than  one 
out  of  three  trials,  which  is  not  a  bad  fit.  So  far,  therefore,  the  avail- 
able data  are  in  fair  accord  with  the  three-factor  hypothesis. 

Before  taking  up  a  consideration  of  the  F3  behavior  of  other  F2  color 
types,  it  will  be  well  to  consider  briefl}'^  the  F4  behavior  of  F3  purple  plants. 
Only  one  F3  pm-ple  of  the  lot  having  all  six  color  types  (table  8,  group  1), 
comparable  to  F2  purples,  was  tested  in  F4.  This  one  plant  gave  an  F4 
with  the  four  color  types  la,  Ila,  V,  and  Via. 

Onty  eight  other  F3  purple  plants  were  tested  in  F4.  All  these  belonged 
to  the  lot  consisting  of  color  types  la.  Ilia,  V,  and  VIb  (group  4,  table  8). 
The  F2  purple  plants  giving  rise  to  this  group  are  assumed  to  have  been 
of  the  genotype  AaBb  PI  PL  The  Fj  purple  plants  should  therefore 
have  been  of  four  genotypes  and  should  have  given  F4  behavior  as 
follows: 


Plant  Colors  in  Maize 


39 


Fi  color  types 

F3  genotypes 

Purple 
la 

Dilute 

purple 

Ilia 

•  Brown 
V 

Green 
Vib 

1  — A  ABB  PI  PI 

1 
3 
3 
9 

i 

3 

1 

3 

2~AABb  PI  PI 

2  —  AaBBPlPl 

A~AaBb  PlPl 

1 

The  data  are  presented  in  table  9.  Four  F4  progenies  (group  1)  were 
made  up  of  the  four  color  types  la,  Ilia,  V,  and  VIb.  The  total  numbers 
of  plants  of  each  of  the  four  types,  as  seen  below,  were  in  close  accord 
with  expectation,  P  equaling  0.57.  There  is  more  than  an  even  chance 
that  such  deviations  as  those  observed  may  have  been  due  to  errors 
of  random  sampling.  The  comparison  of  observed  with  calculated  results 
follows : 

Color  types  Purple        ^  .'^^  j^      Brown      Green     Total 

la  Illa  V  VIb 

Observed 185  68  74  20  347 

Calculated 195  65  65  22  347 

Difference —10  +3  +9  —2  0 

Three  of  the  eight  purple  Fs's  (group  2)  gave  in  F4  only  purple  and 
dilute  purple  plants,  88  of  the  former  and  28  of  the  latter.  The  expected 
numbers  were  87  and  29,  respectively,  showing  a  deviation  of  1  ±3.1. 

One  of  the  eight  F3  purples  (group  3)  gave  67  purple  and  21. brown 
plants  in  Fj,  while  the  expected  niunbers  were  66  and  22,  respectively. 
The  deviation  here  is  only  1  ±  2.7. 

None  of  the  eight  F.-^  purples  Ijred  true,  but  only  one  in  nine  was  expected 
to  do  so.  As  already  indicated,  the  theoretical  distribution  of  nine  F3 
purples  of  the  sort  here  under  consideration,  with  respect  to  the  four 
kinds  of  behavior  in  F4,  is  1:2:2:4.  The  observed  distril)Ution  was 
0:3:1:4.  There  is  more  than  an  even  chance  that  these  deviations  may 
have  been  due  to  errors  of  random  sampling,  P  equaling  0.57. 


40 


R.  A.  Emerson 


It  should  not  be  forgotten  that,  while  a  very  poor  fit  of  observation  to 
hypothesis,  as  measured  by  values  of  P,  throws  doubt  upon  the  correct- 
ness of  the  hypothesis,  it  does  not  follow  that  a  good  fit  proves  the 
hypothesis  to  be  true.  This  is  particularly  true  where  small  numbers 
are  dealt  with.  It  will  be  recalled  in  this  connection  that,  owing  prol^ably 
to  the  small  numbers  tested,  no  F2  purple  has  been  found  to  breed  true  in 
F3  and  none  has  been  found  to  give  only  purple  and  brown  offspring. 
It  has  been  shown,  however,  that  purple  plants  of  the  genotype 
A  a  B  B  PI  PI  exist,  since  one  F3  purple  threw  only  purple  and  brown 
plants  in  F4.  Moreover,  one  of  these  F4  purples  repeated  this  behavior 
in  F5.  Similarly  it  can  be  said  that  purples  of  the  genotype  A  A  B  B  PI  PI 
have  been  recovered  from  the  crosses  under  consideration,  for  two  F4 
purple  plants  of  the  lot  composed  of  purples  and  dilute  purples  (group  2, 
table  9),  when  backcrossed  to  green,  gave  18  purple  plants  and  no  other 
types  in  the  next  generation,  and  one  of  these  two  F4  purples,  when  crossed 
back  to  dilute  sun  red,  gave  34  purple  plants.  Two  other  purples  of 
the  same  F4  lot,  when  similarly  crossed,  gave  both  purple  and  dilute  pm*ple, 
23  of  the  former  and  18  of  the  latter.  Pm'ple  plants  of  all  the  expected 
genotypes  have  therefore  been  recovered  in  one  or  another  generation 
from  F2  to  F4  from  the  original  crosses  of  purple  x  green  and  dilute  sun 
red  X  brown.  Moreover,  these  genotypes  have  been  found  in  numbers 
not  far  from  what  might  reasonably  be  expected  considering  the  relatively 
small  numbers  tested.  It  now  remains  to  inquire  into  the  F3  and  later 
behavior  of  F2  color  types  other  than  purple. 

Later  behavior  of  F2  sun  red  Ila. —  Sun  red  plants  of  F2  of  the  crosses 
purple  x  green  and  dilute  sun  red  x  brown  are  expected,  in  accordance 
with  the  three-factor  hypothesis,  to  be  of  four  sorts  with  respect  to  their 
behavior  in  F3,   as  follows: 


F2  genotypes 


F3  color  types 


Siin  red 
Ila 


Dilute 

sun  red 

IVa 


Green 
Via,  c 


1  —  AABBplpl. 

2  —  AABbplpL 
2  —  AaBBplpl. 
4  —  A  a  B  bplpl. 


Plant  Colors  in  Maize  41 

Only  nine  Fo  sun  red  plants  wore  tested  by  their  F3  behavior,  and  no 
later  generations  were  si'own.  All  the  available  data  ara  {jfiven  in  table 
10  (page  128).  Five  F2  plants,  when  self-pollinated  (group  1  of  the  table), 
gave  the  expected  three  classes  of  progeny,  sun  red,  dilute  sun  red,  and 
green,  with  a  distribution  of  the  F3  plants  as  given  below,  and  in  addition 
a  single  brown  plant.  To  include  this  unexpected  plant  in  the  compari- 
son with  the  calculated  distril)ution  would  give  zero  as  the  value  of  P, 
which  is  equivalent  to  saying  that  even  in  an  infinite  number  of  trials  there 
is  no  chance  of  finding  such  a  plant  thru  errors  of  random  sampling.  The 
single  off-type  plant  is  readily  accounted  for  by  supposing  that  a  grain  of 
foreign  pollen  was  accidentally  admitted  in  the  pollination  of  the  parent 
plant.  Tho  it  is  realized  that,  with  such  a  convenient  supposition  always 
at  hand,  almost  any  result  can  be  made  to  fit  a  theory,  the  reality  of  just 
such  accidental  pollinations  will  not  be  questioned  ,by  any  one  who  has  had 
experience  in  the  technique  of  maize  pollination.  With  the  elimination 
of  this  one  plant,  the  fit  of  observation  to  hypothesis  is  almost  perfect. 
The  comparison  follows: 

Color  types  Sun  red    ^^^^^^     Green      Total 

Ila  IVa       VIa,c 

Observed 126  42  55  223 

Calculated 125  42  56  223 

Difference +1  0      "    —1  0 

Three  Fo  sun  red  plants,  including  one  of  the  five  in  the  former  test, 
were  crossed  back  to  green  (group  1,  table  10).  The  same  three  color 
types  w^ere  observed  as  in  the  self-pollinated  plants,  with  the  addition 
again  of  a  single  off-type  plant,  this  time  a  purple  one.  Even  if  this  plant 
is  left  out  of  consideration  as  due  to  an  accidental  pollination,  the  fit  of 
observed  with  calculated  numbers  is  not  very  good.  Such  deviations 
from  theoretical  behavior  are  to  be  expected  thru  chance  alone  only  once 
in  eight  trials,  P  equaling  0.12.     The  comparison  follows: 

Color  types                           Sun  red  ^^^^  ^.^^  Green  Total 

Ila  IVa  Via,  c 

Observed 14  18                50  82 

Calculated... 20.5  20.5            41  82 

Difference —6.5      —2.5  +9  0 


42 


R.  A.  Emerson 


A  single  F2  sun  red  plant  (group  2,  table  10)  gave,  from  self-pollination. 
23  sun  red  and  9  dilute  sun  red  F3  plants,  a  deviation  fronri  expectation  of 
1  ±  1.7. 

A  single  Fo  sun  red  plant  (group  3,  table  10),  when  crossed  with  green 
Vic,  gave  50  sun  reds  and  43  greens  where  equality  was  expected,  a  devia- 
tion of  3.5  ±  3.3. 

By  way  of  summary  of  the  behavior  of  Fo  sun  red  plants,  it  must  be 
noted  that,  while  four  sorts  of  behavior  were  expected,  only  three  sorts 
were  observed.  While  any  nine  such  F2  plants  should  be  distributed  with 
respect  to  the  four  kinds  of  behavior  in  the  relation  1:2:2:4,  the  observed 
relation  was  0:1:1:7.  Wliile  mathematically  this  is  not  a  very  bad  fit 
considering  the  small  numbers  involved,  P  equaling  0.24,  it  is  inadequate 
for  a  deteiTQination  of  the  possible  genotypes  of  F2  sun  red  plants. 
Fortunately,  certain  crosses  considered  later  (page  51)  involving  the  sun 
red  type,  with  presumably  the  same  genetic  constitutions  as  the  F2  sun 
reds  of  this  cross,  afford  a  more  nearly  adequate  test  of  the  matter. 

Later  behavior  of  Fo  dilute  purple  Ilia. —  F2  dilute  purple  plants  should 
present  the  same  types  of  behavior  in  F3  as  F2  sun  reds,  but,  of  course, 
with  somewhat  different  color  types  appearing,  as  follows: 


F2  genotypes 


1— A  Abb  PI  PI 
2~AAbbPlpl. 
2  — A  abb  PI  PL 
4~ A  abb  PI pL. 


F3  color  types 


Dilute 

purple 

Ilia 


Dilute 

sun  red 

IVa 


Green 
VIb,  c 


The  available  data  from  this  test  are  given  in  table  11  (page  129).  Four 
F2  dilute  purples  (group  1)  yielded  the  three  color  types  expected,  dilute 
purple,  dilute  sun  red,  and  green,  in  the  numbers  shown  below.  There 
is  considerably  more  than  an  even  chance  that  the  deviations  from  expecta- 
tion may  be  due  to  errors  of  random  sampling,  P  equaling  0.58.  The 
comparison  follows: 


Plant  Colors  in  Maize  43 

r^  1      J.                                          Dilute  Dilute  ri  n.  .   ■, 

C«^o^-*yP^^                                  purple  sun  red  ^''''''  ^^^^^ 

Ilia  IVa  VIb,  c 

Observed 95  31              50  176 

Calculated 99  33              44  176 

Difference —4  —2  +6  0 

One  of  the  dilute  purple  Fo  plants  used  in  this  test  was  backcrossed 
with  green  VIc  (group  1,  table  11),  with  the  result  shown  below.  There 
is  practically  an  even  chance  that  the  observed  deviations  may  be  due  to 
errors  of  random  sampling,   P  equaling  0.49.     The  comparison  follows: 

^  1      ,  Dilute      Dilute      ^  t-  ^  i 

Color  t\T3es  i  ,     ureen        Total 

■^^  purple      sun  red 

Illa         IVa       VIb,  c 

Observed 21  25  57  103 

Calculated 26  26  52  104 

Difference — 5  — 1  +5  — 1 

One  F2  dilute  purple  gave  57  dilute  purple  and  21  dilute  sun  red  plants 
in  Fa  (group  2,  table  11).  The  expected  numbers  were  58.5  and  19.5, 
respectively,  the  deviation  being  1.5  ±  2.6. 

Three  Fo  dilute  purples  gave  a  total  of  85  dilute  purple  and  20  green 
plants  (group  3,  table  11),  the  theoretical  numbers  being  79  and  26, 
respectively.  The  deviation  from  expectation,  6  plants,  is  just  twice  the 
probable  error. 

One  F2  dilute  purple  bred  true  in  F3,  producing  21  dilute  purple  plants 
and  no  other  types  (group  4,  table  11).  Thus,  all  the  sorts  of  behavior 
expected  of  F2  dilute  purples  were  reahzed  in  F3.  The  distribution  of 
the  F2  plants  with  respect  to  the  four  sorts  of  behavior  was  1:1:3:4, 
instead  of  the  theoretical  distribution  1:2:2:4.  Differences  of  this  sort 
might  be  expected  thru  chance  in  four  out  of  five  trials,  P  equaling  0.80. 

Only  three  plants  of  these  lots  were  tested  in  F4.  One  was  a  dilute  sun 
red  of  the  lot  made  up  of  dilute  purples  and  dilute  sun  reds,  and  this  one 
bred  true  in  Fi  as  was  expected  of  it,  producing  34  dilute  sun  red  plants. 
The  other  two  plants  tested  further  were  dihit(,'  purples  of  the  lot  contain- 
ing the  three  color  types  III,  IV,  and  VI.     Both  again  gave  these  three 


44 


R.  A.  Emerson 


types,  the  total  numbers  of  the  respective  classes  being  29,  5,  and  18. 
The  expected  numbers,  29,  10,  and  13,  show  a  deviation  from  expecta- 
tion which  might  result  thru  chance  about  once  in  nine  trials,  P  equaUng 
0.11. 

Later  behavior  of  F^  dilute  sun  red  IVa.—z  Dilute  sun  red  plants  of  F2 
should  be  of  two  sorts,  A  Ahhplpl  and  Aahhpl  j)l.  Five  such  plants 
were  tested,  with  results  as  shown  in  table  12  (page  129).  Of  these  five, 
two  bred  true,  producing  a  total  of  92  dilute  sun  red  plants  (group  2). 
One  of  these  two,  when  backcrossed  with  green,  gave  69  dilute  sun  red 
plants.  Three  of  the  five  F2's  gave  in  F3  dilute  sun  reds  and  greens,  62 
of  the  former  and  17  of  the  latter  (group  1).  The  theoretical  numbers 
were  59  and  20,  respectively.  The  deviation  of  3  plants  is  only  a  httle 
greater  than  the  probable  error,  ±  2.6.  With  two  of  the  F2  dilute  sun  red 
plants  breeding  true  and  three  again  throwing  segregates,  expectation 
was  very  nearly  reahzed. 

Later  behavior  of  F2  brown  V. —  Brown  plants  of  Fo  are  expected  to  be 
of  four  genotypes  and  to  show  consequent  differences  in  behavior  in  F3 
as  follows: 


F3  color  types 


F2  genotypes 


1  —  aaBBPlPl 

2  —  aaBB  Plpl. 
2  —  aaBbPlPl. 
4  —  aaBbPlpl.. 


Data  for  F3  from  fourteen  F2  brown  plants  are  presented  in  table  13 
(page  130).  Five  self-pollinated  F2  browns  (group  1)  gave,  in  addition 
to  one  sun  red  prcsumabl}'-  due  to  accidental  pollination,  96  browns  and 
74  greens  in  F3,  which  is  almost  exactly  a  9 : 7  relation,  the  deviation  being 
0.4  ±  44.  Nine  other  selfed  F2  browns  (group  2)  gave  in  F3  a  total  of  354 
brown  and  104  green  plants.  An  exact  3 : 1  ratio  for  the  total  of  458 
would  be  343.5  and  114.5,  respectively,  the  deviation  being  10.5  ±  6.3. 
Such  a  deviation  might  be  expected  thru  chance  alone  about  once  in  four 


Plant  Colors  in  Maize  45 

trials.  One  of  the  F2  brown  plants  that,  when  solfod,  gave  a  3:1  ratio 
in  F3,  when  crossed  with  green  gave  34  brown  and  41  green  plants  where 
equal  numbers  were  expected,  the  deviation  being  3.5  ±  2.9.  None  of 
the  fourteen  F2  brown  plants  bred  true  in  F3.  The  fourteen  plants  should 
theoreticall}^  have  given  F^  ratios  of  1:0,  3:1,  and  9:7  in  approximately 
the  respective  numbers  of  1.6,  6.2,  6.2,  while  the  observed  numbers  were 
0,  9,  5.  Such  deviations  might  occur  by  chance  once  in  five  trials,  P 
equaUng  0.22. 

It  is  often  difficult  and  sometimes  practically  impossible  from  ordinary 
F3  progenies  to  distinguish  between  the  two  genotypes  of  brown  which 
throw  3:1  progenies,,  namely,  a  a  B  B  PI  pi  and  ao  B  b  PI  PI.  The  green 
plants  thrown  b}^  the  former  often  show  some  brown  pigment  in  the  exposed 
parts  of  the  sheaths  and  husks  (type  Via),  a  condition  not  seen  in  the 
greens  (\Tb)  thrown  ])y  the  latter.  In  some  lots  the  brown  pigment 
is  fairly  conspicuous  but  in  others  it  is  very  weak  or  is  absent.  Again,  the 
greens  of  type  VIb  thrown  by  l^rowns  of  the  genotype  aaBb  PI  PI 
show  considerable  brown  in  the  glumes  of  the  staminate  flowers.  This 
is  particularly  pronounced  when  r<^''  (a  gene  for  cherry  pericarp  which  is 
effective  only  in  the  presence  of  PI)  is  present,  but  when  this  factor  is 
lacking  the  brown  color  is  often  so  faint  that  it  is  impossible  to  distinguish 
between  a  green  plant  carrying  PI  and  one  lacking  it.  If  r''''  is  present, 
the  greeu  plants  carrjnng  PI  develop  a  Ught  brownish  pericarp  at  maturity 
while  those  lacking  PI  never  show  this  pericarp  color  whether  or  not  B 
is  present.  Here  again,  however,  the  hght  brownish  pericarp  due  to 
r^^,  PI,  and  a  a  ma}^  be  wholly  masked  if  there  happens  to  be  present 
another  pericarp  color  gene,  P,  which  with  a  a  brings  about  a  strong 
brown  color  of  the  pericarp  whether  or  not  PI  or  B  is  present.^  On  the 
whole,  therefore,  it  is  difficult,  and  often  impossible,  to  determine  the 
genotype  to  which  a  brown  plant  belongs,  by  an  inspection  of  the  green 
plants  occurring  in  its  progen3^  Because  of  this,  the  3 : 1  lots  of  F3 
progenies  of  Fo  brown  plants  are  lumped  together  in  group  2  of  table  13 
without  any  attempt  to  separate  them  into  the  two  classes  expected. 
Fortunately,  it  is  readily  possible  to  distinguish  between  brown  plants  of 
the  two  genotypes  under  consideration  here  by  means  of  appropriate 
crosses. 


*  An  account  of  these  pericarp-color  factors  is  to  be  published  later  by  Dr.  E.  G.  Anderson,  who  is 
making  a  study  of  the  pericarp  colors  of  maize. 


46 


R.  A.  Emersox 


When  brown  plants  of  all  the  genotypes  expected  in  F2  of  the  crosses 
of  purple  X  green  or  dilute  sun  red  x  brown  are  crossed  with  homozygous 
dilute  sun  red  plants,  the  following  behavior  is  expected  in  the  next 
generation : 


F2  genotypes 


1—aaBB  PlPl 
2~aaB  B  Plpl. 
2^aaBb  PlPl. 
4  —  aaBb  Plpl. 


Purple 
la 


F2  X  A  Abb  pi  pi 


Sun  red 
Ila 


Dilute 

purple 

Ilia 


Dilute 

sun  red 

IVa 


A  few  such  tests  of  F2  brown  plants  are  recorded  in  table  14.  Two  plants 
(group  1),  on  being  crossed  with  dilute  sun  reds,  gave  purples  and  sun 
reds  only,  38  of  the  former  to  45  of  the  latter,  where  equality  was  expected, 
the  deviation  being  3.5  ±  3.1.  One  of  these  plants  has  progeny  from  self- 
pollination  listed  in  table  13,  in  group  2,  the  3:1  lot.  This  plant  was 
expected,  of  course,  to  throw  only  two  color  types  from  the  cross  with 
dilute  sun  reds,  for  otherwise  it  should  not  have  given  a  3 : 1  progeny  on 
being  selfed.  The  two  brown  plants  in  group  1  of  table  14  must  have 
been  aa  B  B  Plpl.  Two  other  F2  brown  plants  (group  2)  gave  32  purple 
and  38  dilute  purple  instead  of  the  equal  numbers  expected,  the  deviation 
being  3.0  ±  2.8.  These  plants  are  assumed  to  have  been  a  a  B  b  PI  PL 
A  single  F2  brown  plant  (group  3)  when  crossed  with  dilute  sun  red  gave 
15  purple  plants,  and  is  therefore  assumed  to  have  been  a  a  B  B  PI  PI. 
The  behavior  of  several  F3  brown  plants  when  crossed  with  dilute  sun 
reds  is  also  shown  in  table  14.  Three  of  these  plants  were  from  9:7  F3 
lots  and  therefore  are  presumably  comparable  with  F2  browns.  One  of 
these  three  (group  4)  gave  the  four  color  types  I  to  IV  in  the  numbers 
1:2:6:3.  It  was  probably  a  a  Bh  Plpl  and  should  have  given  a  9:7 
progeny  if  it  had  been  selfed.  The  other  two  F3  browns  of  the  9:7  lot 
gave  49  purple  plants  (group  7)  and  are  consequently  regarded  as 
aaB B  PI  PL     All  the  other  F3  brown    plants  tested    were    from   the 


Plant  Colors  in  Maize  47 

3:1  lot  listed  in  table  13,  group  2.  None  of  these  should  give  more  than 
two  types  when  crossed  with  dilute  sun  red.  One  gave  46  purple  and 
1  dilute  sun  red  (group  7),  the  latter  doubtless  from  an  accidental 
poUination  of  the  dilute  sun  red  mother  plant.  Two  F3  browns  gave  22 
purple  and  24  sun  red  plants  (group  5),  and  four  produced  73  purple  and 
85  dilute  purple  plants  (group  6). 

To  summarize,  all  the  theoretically  possible  genotypes  of  brown  plants 
have  been  found  either  in  F2  or  in  such  F3  lots  as  showed  a  9:7 
ratio  of  brown  to  green.  Since  these  Fs's  are  comparable  with  F2  browns, 
thej^  maj^  be  added  to  the  F2's  in  this  summary.  Of  the  twenty-one 
brown  plants  thus  grouped,  the  numbers  found  to  belong  to  each  geno- 
tj^pe  are  compared  below  with  the  calculated  numbers.  The  deviations 
are  such  as  might  be  expected  to  occur  once  in  three  trials,  P  equaling 
0.34.     The  comparison  follows: 

aciBBPl  j)l 
aaB  B  PI  PI  or  a  a  B  h  PI  pi      Total 

aaBbPl  PI 

Observed 3  12  6  21 

Calculated 2.3f+)  9.3(+)  9.3(+)  21 


Difference +0.7(-)  +2.7(-)  — 3.3(+)  0 

Later  behavior  of  F2  green  VI. —  All  Fo  green  plants  should  breed  true 
phenotypically  in  F3.  Data  from  eight  such  F3  progenies  are  given  in 
table  15,  group  1  (page  132).  There  were  observed  a  total  of  179  green 
plants,  and  no  other  tjq^es.  Progenies  of  sixteen  green  plants  of  the 
F2  lots  listed  in  tables  3  and  6  (pages  122  and  124),  produced  l^y  backcrossing 
Fi  purples  to  greens,  are  given  in  table  15,  groups  2  to  5.  The  total 
number  of  green  plants  in  these  progenies  is  311.  A  single  brown  plant 
found  in  one  of  these  progenies  is  assumed  to  have  been  due  to  acci- 
dental pollination.  Green  plants  are  thert'fore  found  to  breed  true  green 
as  expected,  but  there  is  nothing  in  this  fact  to  indicate  that  green  plants 
of  the  crosses  under  consideration  are  genotypically  alike.  That  the 
five  genotypes  expected  on  the  basis  of  the  three-factor  hypothesis  were 
present  among  the  progenies  hsted  in  table  15  is  demonstrated  in  the 
next  section  of  this  paper. 


48  R,.  A.  Emerson 

Intercrosses  of  F^  color  types 

It  has  been  shown  in  the  preceding  pages  that  all  the  six  color  tj^pes 
occurring  in  F2  of  a  cross  between  purple  and  green  behave  in  F3  and  later 
generations  as  is  expected  on  the  basis  of  the  three-factor  hypothesis 
suggested  to  account  for  the  F2  results.  It  remains  to  determine  whether 
the  several  color  types  behave  in  accordance  with  the  hypothesis  when 
intercrossed  one  with  another.  Of  the  fifteen  possible  intercrosses  between 
phenotypically  different  types,  two  have  already  been  discussed.  The 
cross  of  purple  with  green  has  formed  the  basis  of  the  whole  discussion. 
The  cross  of  dilute  sun  red  with  brown,  since  it  was  expected  to  give  the 
same  results  as  the  original  cross  of  purple  with  green,  was  most  conven- 
iently considered  with  that  cross  in  generations  later  than  F2.  The  results 
of  this  second  cross  have  been  in  accord  with  expectation.  The  other 
thirteen  intercrosses  are  now  to  be  considered,  together  with  intercrosses 
of  some  types  that  are  phenotypically  alike. 

Dilute  sun  red  IVa  x  green  Via.  VIb,  Vic. —  The  progenies  of  self- 
pollinated  green  plants  were  listed  in  table  15  in  several  groups  in 
accordance  with  what  was  learned  of  their  genotypic  constitution  by  the 
crosses  to  be  considered  here.  The  regular  F3  lots,  from  self-pollinated 
F2  greens  of  self-pollinated  Fi  purples,  were  put  in  group  1  of  table  15. 
Only  one  of  the  same  F2  greens  (table  16,  group  2)  was  crossed  with  homo- 
zygous dilute  sun  red,  A  Ahhpl  pi.  The  result  was  67  dilute  purple 
plants.  Another  green  plant,  an  F3  from  a  self-pollinated  F2  green,  gave, 
when  similarly  crossed,  9  dilute  purple  plants  (group  2).  Evidently  both 
these  green  plants  were  a  abb  PI  PI.  Four  other  F3  green  plants,  when 
crossed  with  dilute  sun  red,  gave  a  total  of  148  sun  red  plants  (group  1, 
table  16).  One  of  these  four  belonged  to  an  F3  lot  containing  browns  and 
greens  in  a  3:1  relation,  and  could  not,  theoretically,  have  done  other 
than  give  all  sun  red  or  all  dilute  purple  when  crossed  with  dilute  sun  red. 
Two  of  the  four  were  from  greens  of  an  F3  lot  made  up  of  purples,  sun  reds, 
browns,  and  greens,  and  were  therefore  assumed  to  be  aa  B  B  pl  pl, 
as  the  crosses  with  dilute  sun  red  showed  them  to  be.  One  of  the  four 
green  plants,  however,  belonged  to  an  F3  lot  of  browns  and  greens  in  a 
9:7  relation  and  was  consequently  comparable  to  an  F2  green.  A  sixth 
F3  green  also  belonged  to  a  9 : 7  lot,  comparable  to  an  F2  lot.  When  crossed 
with  dilute  sun  red  (group  3,  table  16),  it  gave  24  dilute  sun  red  plants, 


Plant  Colors  in  Maize  49 

and  is  therefore  assumed  to  have  been  a  abb  yl  pi.  All  three  of  the 
theoretically  possible  homozygous  genotypes  have  therefore  been  demon- 
strated among  the  Fo  greens  or  among  Fs's  comparable  to  F2's. 

In  addition  to  the  green  plants  of  the  direct  Fo  and  F.s  generations, 
noted  above,  fifteen  other  greens  were  crossed  with  dilute  sun  red.  All 
these  greens  belonged  to  a  single  progeny,  2019,  which  was  the  result  of  a 
backcross  of  an  Fi  purple  with  a  green,  a  abb  pi  pi  (table  3,  group  1). 
All  of  them  should  therefore  have  been  heterozygous  for  B  or  PI,  or  have 
lacked  these  dominant  genes.  Seven  of  the  fifteen,  when  crossed  with 
dilute  sun  red,  gave  110  sun  red  and  85  dilute  sun  red  plants  (group  4, 
table  16),  a  deviation  from  equality  of  12.5  ±  4.7.  The  green  parent 
plants  are  consequently  regarded  as  a  a  B  b  pi  pi.  Five  others  of  the 
fifteen  green  plants  (group  5)  gave  a  total  of  50  dilute  purple  and  65 
dilute  sun  red,  a  deviation  from  equality  of  4.5  ±  3.7,  and  hence  are  assmned 
to  have  been  a  abb  PI  pi.  Three  of  the  fifteen  (group  6)  gave  a  total  of 
106  dilute  sun  red  plants.  These  three  must,  it  is  supposed,  have  been 
a  abb  pi  pi. 

Naturally,  in  the  course  of  the  writer's  maize  studies,  many  other 
crosses  between  green  and  dilute  sun  red  have  been  observed.  But  no 
purpose  can  be  served  by  presenting  here  all  this  mass  of  data.  Much 
of  it  has  accumulated  in  connection  with  a  study  of  the  interrelations  of 
plant  and  aleurone  color,  and  will  find  its  appropriate  place  in  a  later 
publication  on  that  topic.  A  few  Fo  and  backcross  progenies  of  dilute  sun 
red  Fi's  of  such  ciosses  are,  however,  listed  in  table  17  (page  134),  to  serve 
as  an  indication  of  the  behavior  of  all.  Three  F.;  progenies  (group  1,  table 
17)  contained  269  dilute  sun  reds  and  99  greens,  a  deviation  from  the 
expected  3: 1  ratio  of  7  ±  5.6.  Five  progenies  of  Fi  dilute  sun  reds  back- 
crossed  to  green  Vic  (group  2)  included  357  dilute  sun  reds  and  358  greens, 
a  deviation  from  the  expected  1 : 1  ratio  of  only  0.5  ±  9.0. 

The  behavior  of  a  number  of  the  sun  red  and  dilute^  purple  plants  listed 
in  table  16  has  been  studied  in  F2  and  later  generations.  Consideration 
of  this  later  behavior  is  conveniently  deferred  to  a  later  section  of  this 
paper  (pages  51  and  53),  where  it  is  taken  up  with  other  crosses  which 
should  theoretically  give  similar  results. 

Green  x  green.  Via,  VIb,  Vic. —  A  number  of  green  plants  of  progcMiy 
2019,  discussed  above,  were  intercrossed.  That  these  green  plants  l)rcd 
true  green  when  selfed  was  shown  by  the  records  of  table  15  (groups  3 


50  R.  A.  Emerson 

to  5) .  That  they  were  of  three  distinct  genotypes  was  shown  by  the  data 
recorded  in  table  16  (groups  4  to  6).  The  behavior  of  random  intercrosses 
of  the  same  green  plants  is  now  to  be  considered.  The  data  are  given  in 
table  18. 

The  green  plants  that  served  as  parents  of  the  crosses  listed  in  group 
6  of  table  16,  it  was  decided,  must  have  been  a  a  bbpl  jd.  When  such 
plants  are  crossed  with  green  plants  of  any  of  the  other  genotypes,  nothing 
but  green  plants  should  result.  A  single  cross  of  one  of  these  greens  with 
a  green  of  the  constitution  a  a  B  b  pi  pi  (table  16,  group  4)  gave  23  green 
plants  (table  18,  group  1)  as  expected.  Another  cross  of  one  of  these 
greens  with  a  green  of  the  genotype  a  abb  PI  pi  (table  16,  group  5)  gave 
22  green  plants  (table  18,  group  2).  Crosses  of  green  plants  belonging 
to  like  genotypes  should,  of  course,  give  only  green  plants.  Three  crosses 
of  plants  shown  to  be  a  a  5  6  pi  pi  (table  16,  group  4)  gave  72  green  plants 
(table  18,  group  3) .  A  single  cross  between  plants  shown  to  be  a  ah 
b  Pi  pi  (table  16,  group  5)  gave  24  green  plants  (table  18,  group  4).  Five 
crosses  of  plants  of  genotype  a  a  B  b  pi  pi  with  plants  of  genotype 
a  abb  PI  pi  gave  a  total  of  40  brown  and  105  green  plants  (table  18, 
group  5).  Here  a  1:3  ratio  of  brown  to  green  is  to  be  expected.  The 
theoretical  numbers  are  therefore  36  and  109,  respectively,  and  the  devia- 
tion is  4.0  ±  3.5.  The  important  fact  here  is  that  all  these  intercrosses  of 
greens  gave  the  color  types  expected  on  the  basis  of  the  results  of  crosses 
of  the  same  individual  green  plants  with  dilute  sun  reds.  The  writer 
deems  himself  fortunate  in  having  been  able  to  obtain  results  approxunat- 
ing  so  closely  a  complete  demonstration  of  the  several  genotypes  of 
green,  since  the  selfing,  the  crossing  with  dilute  sun  reds,  and  the  inter- 
crossing of  greens,  were  made  at  the  same  time,  with  the  green  plants 
chosen  wholly  at  random. 

Brown  V  x  green  Vic. —  When  brown  plants  are  crossed  with  green 
plants  of  type  Vic,  the  Fi  plants  arc  brown,  and  browns  and  greens  alone 
appear  in  F2.  Since  brown  is  supposed  to  be  a  B  PI  and  type  Vic  green 
a  b  pi,  the  F2  progenies  should  exhibit  9 : 7  ratios.  Eleven  F2  progenies 
are  listed  in  table  19  (page  135),  with  a  total  of  317  brown  and  223  green 
plants.  The  theoretical  numbers  are  304  and  236,  respectively,  showing 
a  deviation  of  13  ±  7.8.  There  is  more  than  one  chance  in  four  that  such 
a  deviation  is  due  to  errors  of  random  sampling,  P  equaling  0.27. 


Plant  Colors  in  Maize  51 

Of  any  nine  F2  brown  plants  of  this  cross,  theoretically  one  should 
breed  true  in  F3,  four  should  give  a  3:1  ratio,  and  four  should  give  a  9:7 
ratio.  Six  F^'s  were  tested,  with  the  results  shown  in  table  20.  Two 
bred  true,  with  a  total  of  29  brown  plants  (group  1).  Two  gave  ratios 
classed  as  3:1,  the  totals  (group  2)  being  100  brown  to  40  green,  a  devia- 
tion of  5.0  ±  3.5.  Two  gave  progenies  interpreted  as  9:7  (group  3), 
totaling  39  l)rown  and  39  green,  the  deviation  being  5.0  ±  3.9.  Of  the 
3:1  Fs  lot,  two  browns  bred  true  in  F4,  producing  59  brown  plants,  and 
one  green  l^red  true,  producing  56  green  plants. 

The  distribution  of  the  F2  brown  plants  with  respect  to  their  F3  behavior 
—  two  breeding  true,  two  throwing  a  3:1  ratio,  and  two  a  9:7  ratio  — 
was  as  near  expectation,  1:4:4  in  nine,  as  could  perhaps  be  expected  from 
such  small  nimibers.  If  these  six  F2  browns  are  combined  with  the  four- 
teen F2  browns  of  the  original  cross  of  purple  x  green  noted  earlier  in  this 
paper  (page  44),  a  very  good  fit  of  the  hypothesis  and  observation  is  found 
(z2  =  0.88).  Theoretically  these  two  lots  of  F2  browns  should  be  of  the 
same  genotypes,  so  that  they  may  well  be  so  combined.  The  comparison 
follows : 

F3  ratios  1:0  3:1  9:7     Total 

Observed 2  11  7  20 

Calculated 2  9  9  20 

Difference 0+2  —2  0 

Sun  red  II a  x  green  Vic—  When  both  parents  are  homozygous,  the 
cross  of  green  of  type  Vic  with  sun  red  results  in  sun  red  plants  only. 
Three  such  crosses  gave  112  sun  red  plants.  Crosses  with  heterozygous 
sun  red  plants  gave  Fi  progenies  of  sun  red  together  with  dilute  sun  red 
or  green  or  both,  depending  presumably  upon  whether  one  or  the  other 
or  both  of  the  factors  A  and  B  were  heterozygous.  Fi  sun  red  plants  of 
such  crosses  are  presumed  to  have  the  formula  AaBhpl-pl,  and  should 
therefore  produce  in  F2  the  three  color  types  sim  red,  dilute  sun  red,  and 
green,  in  the  relation  9:3:4.  Sixteen  F2  progenies  of  such  crosses  are 
listed  in  table  21,  group  1  (page  136).  It  has  already  been  shown  (page 
48)  that  crosses  of  some  green  plants,  a  B  pi,  with  dilute  sun  reds,  A  h  pi, 
give  sun  red  Fi  offspring,  which  are  also  assumed  to  be  A  a  Bh  pi  pi. 
Five  F2  progenies  of  such  crosses  are,  for  convenience,  considered  here 


52  R.  A.  Emerson 

(group  2,  table  21)  with  the  crosses  of  sun  red  and  green.  While  certain 
of  the  individual  progenies,  due  perhaps  to  the  small  numbers  concerned, 
deviate  considerabl}^  from  the  expected  results,  the  twenty-one  progenies 
(groups  1  and  2,  table  21)  taken  together  approach  so  closely  to  expectation 
that  there  is  more  than  one  chance  in  four  that  the  observed  deviations 
may  be  due  to  errors  of  random  sampling,  P  equaling  0.28.  The  com- 
parison of  observed  with  expected  numbers  follows: 

Color  types  Sun  red   g^^j^^Vg^i     Green  Total 

Ila  IVa  Via,  c 
Observed : 

Ila    xVIc 827  268  383           1,478 

IVa  X  Via 343  120  179              642 

Total 1,170  388  562  2,120 

Calculated 1,193  398  530  2,121 

Difference —23        —10        +32  —1 

Fi  sun  red  plants,  A  a  B  h  pi  pi,  were  also  backcrossed  with  green  plants 
of  type  Vic,  a  b  pi.  Fifteen  progenies  of  these  backcrosses  are  listed  in 
table  21,  the  progenies  from  the  cross  Ila  x  Vic  in  group  3  and  those  from 
the  cross  IVa  x  Via  in  group  4.  The  expected  relation  of  1:1:2  was 
realized  fairly  well  in  the  results,  the  odds  against  the  observed  devia- 
tions' being  due  to  chance  being  about  three  to  two,  P  equaling  0.39. 
The  observed  and  expected  results  are  compared  as  follows: 

.    Color  types  Sun  red   ^^"^^^^     Green         Total 

Ila  IVa  Via,  c 
Observed : 

(Ila  x  Vic)  X  Vic 134  123  267              524 

(IVa  X  Via)  X  Vic 442  465  962           1 ,869 

Total 576  588       1 ,229  2 ,393 

Calculated 598  598       1 .196  2 ,392 

Difference —22        —10        +33  +1 


Plant  Colors  in  Maize  53 

Dilute  purple  Ilia  x  green  Vic. —  Since  dilute  purple  differs  from  sun 
red  merely  in  having  the  dominant  PI  factor  instead  of  B,  crosses  of  dilute 
purple  with  green  of  type  Vic  should  behave  just  as  did  the  crosses  con- 
sidered in  the  preceding  section,  except  that  dilute  purples  take  the  place 
of  sun  reds  in  the  progeny.  Eight  crosses  of  dilute  purple  with  green  of 
type  Vic  resulted  in  91  dilute  purple  plants.  The  F2  results  of  these 
crosses  are  given  in  table  22,  group  1.  Since  the  Fi  plants  of  these  crosses 
are  assumed  to  have  been  A  ah  b  PI  pi,  the  F2  results  should  be  the  same 
as  those  expected  from  crosses  of  greens  of  type  VIb  with  dilute  sun  reds. 
The  Fi's  of  the  latter  crosses  have  already  been  discussed  (page  48).  The 
F2  results,  six  progenies,  are  for  convenience  considered  here  (group  2, 
table  22) .  "Wliile  the  expectation  of  a  9 : 3 : 4  relation  was  not  very  closely 
realized  in  the  ol)served  results,  such  deviations  as  those  found  might  be 
expected  thru  chance  about  once  in  eight  trials,  P  equaling  0.13.  The 
comparison  of  observed  and  expected  distributions  follows: 

Color  types  ^^^   ^    G.een         Total 

Ilia  IVa  VIb,  c 
Obsei'ved : 

Ilia  X  Vic 416  149  173               738 

IVa  x  VIb 274  102  107               483 

Total 690  251  280  1 ,221 

Calculated 687  229  305  1,221 

Difference +3        +22        —25  0 

A  single  Fi  plant  backcrossed  with  green  gave  the  same  three  color  types 
in  the  relation  26:20:56.  The  theoretical  distribution  is  25.5:25.5:51.0. 
Deviations  of  the  observed  order  might  be  expected  somewhat  more  than 
twice  in  five  trials,  P  equaling  0.44. 

Seven  F2  greens  bred  true  in  F3  with  a  total  of  359  individuals.  One 
dilute  sun  red  F2  plant  bred  true  with  a  progeny  of  156  dilute  sun  red 
plants.  Of  the  F2 -dilute  purples,  some  bred  true,  some  threw  the  three 
types  seen  in  F2,  some  gave  only  dilute  purple  and  dilute  sun  red,  and 
some  gave  only  dilute  purple  and  green.  Notwithstanding  the  rather 
poor  fit  in  F2,  therefore,  the  fact  that  practically  all  the  expected  .classes 


54  R.  A.  Emerson 

of  behavior  were  exhibited  in  F3  makes  it  seem  Ukely  that  the  deviations 
in  F2  were  due  mainly  to  chance. 

Sun  red  II a  x  brown  V. —  A  single  cross  of  brown  with  sun  red  gave 
purple  plants  only,  as  was  expected.  Since  both  parents  were  homozygous, 
all  the  Fi  plants  should  have  been  of  the  genotype  Aa  B B  Plpl  and 
should  have  produced  in  F2  the  four  types  purple,  sun  red,  brown,  and 
green,  in  the  relation  9:3:3:1.  The  three  F2  progenies  of  this  cross  are 
recorded  in  table  23  (page  137).  The  expected  color  types  were  produced 
in  approximately  the  expected  numbers.  The  odds  against  the  observed 
deviations'  being  due  to  chance  are  three  to  two,  P  equaling  0.40.  A 
comparison  of  observed  with  expected  distributions  follows: 

Color  types  Purple    Sun  red    Brown      Green  Total 

la  Ila  V  Via 

Observed 120  29  37  10  196 

Calculated 110  37  37  12  196 

Difference +10  —8  0  —2  0 

Purple  la  x  brown  V . —  Crosses  of  brown  with  purple  gave  purple 
Fi's,  and  four  F2  progenies  gave  a  total  of  116  purple  and  38  brown  plants, 
which  is  very  near  the  3:1  ratio  expected  from  Fi  plants  of  the  genotype 
A  a  B  B  PI  PI,  the  deviation  being  0.5  ±  3.6.  Nine  Fi  purples  backcrossed 
to  browns  gave  progenies  totaling  484  purple  and  477  brown  plants,  a 
deviation  from  the  expected  equality  of  3.5  ±  10.5. 

Purple  la  x  sun  red  Ila. —  Purples  and  sun  reds  should  differ  by  a 
single  factor  pair,  PI  pi.  The  Fi  purples  backcrossed  to  sun  red  should 
give  a  1 : 1  ratio  of  the  parental  types.  Five  such  backcrosses  gave  47 
purple  and  57  sun  red  plants,  a  deviation  from  expectation  of  5  ±  3.4. 
No  progenies  of  selfed  Fi's  were  observed. 

Purple  la  x  dilute  purple  Ilia. —  Purples  are  assumed  to  differ  from 
dilute  purples  by  the  factor  pair  B  b.  Six  Fi  purples  backcrossed  with 
dilute  purple  gave  40  purple  and  52  dilute  purple  plants.  This  is  a 
deviation  from  the  expected  equaUty  of  6  i  3.2.  No  other  tests  of  the 
cross  of  purple  x  dilute  purple  were  made. 

Sun  red  Ila  x  dilute  sun  red  IVa. —  Sun  reds  and  dilute  sun  reds  should 
differ  in  one  factor  pair,  B  b,  and  should  therefore  give  a  simple  3 : 1  result 
in  F2.  The  Fi  generation  of  six  crosses  of  these  color  types  consisted 
of  135  sun  red  plants.     Sixteen  F2  progenies  Hsted  in  group  1  of  table  24 


Plant  Colors  in  Maize  55 

(page  138)  totaled  998  sun  rod  and  314  dilute  sun  red,  a  deviation  from 
the  3:1  ratio  of  14  db  10.6. 

Fourteen  backcrosses  of  Fi  sun  red  plants  with  dilute  sun  reds  (group  2, 
table  24)  resulted  in  811  sun  reds  and  742  dilute  sun  reds,  a  deviation 
from  the  expected  equality  of  34.5  13 ±.3. 

Two  F2  dilute  sun  reds  bred  true  in  F3  as  expected  (table  25,  group  1), 
with  a  total  of  50  dilute  sun  red  offspring.  Two  F2  sun  red  plants  (group  2) 
gave  a  total  of  19  sun  reds  in  F3,  and  a  third  F2  plant,  on  backcrossing 
with  dilute  sun  red,  gave  101  sun  reds.  Four  other  F2  sun  red  plants 
gave  both  sun  reds  and  dilute  sun  reds  in  their  F3  progenies  (group  3), 
the  respective  numbers  being  373  and  127;  the  calculated  numbers  are 
375  and  125,  respectively,  showing  a  deviation  of  2  ±  6.5.  Of  the  seven 
F2  sun  reds  tested,  four  were  heterozygous  and  three  apparently 
homozygous  for  the  B  factor.  On  the  whole,  therefore,  the  crosses  of 
sun  red  with  dilute  sun  red  behaved  approximately  as  expected. 

Dilute  purple  Ilia  x  dilute  sun  red  IV a. —  Five  crosses  of  dilute  sun 
red  with  dilute  purple  gave  a  total  of  344  Fi  plants,  all  dilute  purple. 
Since  these  Fi's  are  supposed  to  be  heterozygous  for  the  PI  factor  only, 
a  3:1  Fo  distribution  of  color  types  should  result.  Seven  F2  progenies 
Usted  in  group  1  of  table  28  (page  139)  had  a  total  of  261  dilute  purple 
and  87  dilute  sun  red  plants,  exactly  a  3:1  relation.  Five  Fi  plants  were 
backcrossed  with  dilute  sun  red  (group  2)  and  resulted  in  275  dilute 
purples  and  263  dilute  sun  reds.  The  deviation  from  the  theoretical  1 : 1 
relation  is  6  ±  7.8. 

Only  two  F2  dilute  purples  were  tested  by  their  F3  behavior.  Neither 
bred  true,  the  total  produced  being  38  dilute  purples  to  17  dilute  sun  reds, 
a  deviation  from  the  3:1  ratio  of  3.3  ±  2.2.  As  far  as  they  go,  then, 
the  results  are  in  close  agreement  with  what  is  expected  of  the  crosses 
here  under  consideration. 

Sun  red  Ila  x  dilute  purple  Ilia. —  Theoretically,  crosses  of  sun  red, 
A  B  pi,  with  dilute  purple,  A  b  PI,  should  give  purple,  A  B  PI,  in  Fi. 
Two  crosses,  as  shown  in  group  1  of  table  27  (page  140),  gave  a  total  of 
24  purple  and  no  other  types.  Here  the  parents  were  doubtless 
homozygous.  If  one  or  the  other  of  the  panMits  is  heterozygous^  two 
color  types  are  to  be  expected  in  Fx.  A  single  cross  (group  2.  table  27) 
gave  74  purple  and  75  sun  red  plants.  Such  a  result  is  to  l)e  expected  when 
the  sun  red  parent  is  homozygous,  A  A  B  B  pl  pi,  and  the  dilute  purple 
parent  is  heterozygous,  A  Abb  PI  pl.     Two  other  crosses  (group  3)  gave 


56  R.  A.  Emerson 

a  total  of  28  purple  and  29  dilute  purple  plants.  The  parents  are  therefore 
assumed  to  have  been  A  A  B  h  pi  pi  and  A  A  hb  PI  PI,  tho  the  same 
results  should  have  been  obtained  if  one  or  the  other,  but  not  both, 
of  the  parents  had  been  A  a.  The  important  point  here  is  that  purple 
plants  were  produced  in  all  crosses,  showing  that  sun  red  and  dilute  purple 
carry  complementary  factors  for  purple.  The  factors  are  assumed,  in 
keeping  with  the  hypothesis  under  test,  to  be  B  and  PI. 

In  accordance  with  this  hypothesis,  the  Fi  purple  plants  should  be 
A  A  B  b  PI  pi  and  should  throw  four  color  types  in  F2.  No  direct  F2 
progenies  have  been  observed^  but  seven  progenies  from  backcrosses 
of  Fi  purples  with  dilute  sun  reds  are  recorded  in  table  28.  While  the 
deviations  from  the  expected  equality  among  the  four  classes  are  rather 
large,  they  are  not  greater  than  might  occur  by  chance  about  once  in 
four  trials,  P  equaling  0.26.     The  comparison  follows: 

Color  types  Purple     Sun  red     ^^^"l""     ^'^^'^^        Total 

''^  ^  purple     sun  red 

la  Ila  Ilia  IVa 

Observed 99  110  104  83  396 

Calculated 99  99  99  99  396 

Difference 0         +11  +5        —16  0 

Purple  la  x  dilute  sun  red  IVa.—  Crosses  of  purple  with  dilute  sun  red 
should  give  purple  Fi  plants,  A  A  B  b  PI  pi,  and  9:3:3:1  F2  progenies. 
Four  such  crosses  resulted  in  65  purple  plants  in  Fi.  The  F2  results  are 
reported  in  table  29,  group  1.  The  distribution  of  the  individuals  of  the 
twenty-six  progenies  taken  together  is  shown  below  in  comparison  with 
the  calculated  distribution.  The  four  color  types  expected  were  observed 
in  approximately  the  expected  numbers.  Deviations  such  as  shown  might 
be  expected  thru  chance  about  twice  in  eleven  times,  P  equaling  0.18. 

Color  types  Purple    Sun  red     ^'*"f^     ^^^"*^,  Total 

•^  ^  ^  purple     sun  red 

la  Ila  Ilia         IVa 

Observed 1 ,013  316       •  296  100  1 ,725 

Calculated 970  323  323  108  1 ,724 

Difference +43  —7        —27  —8  +1 


Plant  Colors  in  Maize  57 

Some  of  the  Fi  purple  plants  were  crossed  back  to  dilute  sun  red,  with 
results  as  given  in  group  2  of  table  29  and  sumnmrized  below.  The 
seventeen  progenies  together  approached  the  expected  equality  of  the 
four  color  types  so  closely  that  the  observed  deviations  might  be  expected 
thru  chance  more  than  twice  in  five  trials,  P  equaling  0.44. 

Color  types  Purple   Sun  red    ^^^^^^     ^^^"^^,        Total 

•^  ^  ^  purple     sun  red 

la  Ila  Ilia         IVa 

Observed 323  306  325  289  1 ,243 

Calculated 311  311  311  311  1,^4 


Difference +12  —5         +14        —22  —1 

Sixteen  Fo  purple  plants  were  tested  b}^  their  Fs  progenies  (table  30). 
Seven  F2  purples  (group  1)  gave  again  the  four  color  types  purple,  sun 
red,  dilute  purple,  and  dilute  sun  red,  the  several  classes  being  I'epresented 
by  268,  105,  78,  and  28  individuals,  respectively,  while  the  calculated 
numbers  were  269,  90,  93,  and  30.  The  odds  against  such  deviations 
being  due  to  chance  are  about  three  to  one,  P  equaling  0.24.  One  of  the 
seven  F2  purple  plants  was  crossed  with  green  a  abb  pi  pi  and  gave  the 
same  four  classes  of  progeny,  represented  by  26,  25,  24,  and  21  plants, 
respectively.     Evidently  these  F2  purples  were  like  the  Fi's,  A  A  Bb  PI  pi. 

Four  other  F2  purples  (group  2,  table  30)  gave  only  purple  and  sun 
red  progenies.  Three  of  these  when  sclfed  gave  60  purple  and  22  sun  red. 
Two  of  these  three  and  one  other,  when  backcrossed  with  dilute  sun  red 
or  green,  gave  32  purples  and  31  sun  reds.  The  four  F2's  are  therefore 
regarded  asAABBFl pl. 

Five  F2  purples  (group  3)  gave  purples  and  dilute  purples  only.  Four 
of  these,  which  were  selfed,  gave  162  purples  and  48  dilute  purples,  while 
the  fifth,  which  was  backcrossed  to  dilute  sun  red,  gave  17  purples 
and  15  dilute  purples.  These  five  F2's  are  consequently  regarded  as 
AABb  PI  PI. 

None  of  the  sixteen  F2  purples  tested  bred  true  in  F.-),  A  A  B  B  PI  PI. 
A  single?  F3  purple  (group  6),  however,  which  occurred  in  the  ¥i  lot  showing 
the  four  color  tj^pes  (group  1)  and  which  was  therefore  comparable  to 
the  F2  purples,  Ijrcd  true  in  Fi,  pi-oducing  69  purples  on  being  selfed  and 
18  on  being  backcrossed  to  green.     Of  three  other  F3  purples  of  the  same 


58  R.  A.  Emerson 

Fs  lot,  two  (group  4)  gave  only  purples  and  sun  reds,  and  one  (group  5) 
gave  only  purples  and  dilute  purples. 

The  twenty  .Fo  and  Fs  purples  tested,  therefore,  were  distributed  with 
respect  to  the  four  kinds  of  behavior  in  the  relation  7:6:6:1,  in  contrast 
to  the  calculated  distribution  of  approximately  8.9:4.4:4.4:2.2.  There  is 
more  than  an  even  chance  that  such  a  difference  may  be  due  to  errors 
of  random  sampling,  P  equaling  0.53.  On  the  whole,  therefore,  the  F2 
purples  of  this  cross  behaved  in  later  generations  as  was  expected  of 
them. 

F2  sun  red  plants  of  the  cross  purple  x  dilute  sun  red  showed  two  types 
of  behavior  in  F3  (table  31,  group  1).  Three  Fo's  bred  true,  with  53  sun 
red  plants  in  F3.  Four  gave  a  total  of  70  sun  red  and  24  dilute  sun  red 
plants.  Where  an  expected  ratio  of  one  true  breeding  to  two  segregating 
progenies  was  expected,  the  observed  relation  of  three  to  four  is  not  a  bad  fit. 

F2  dilute  purples  also  showed  the  two  types  of  behavior  expected  in 
F3  (group  2,  table  31).  Three  bred  true,  with  a  total  of  97  dilute  purple 
plants,  and  six  gave  a  total  of  217  dilute  purple  and  86  dilute  sun  red 
plants.     The  1:2  ratio  was  therefore  exactly  realized. 

Three  F2  dilute  sun  reds  bred  true  in  F3  (group  3)  as  was  expected 
of  them,  producing  a  total  of  72  dilute  sun  red  plants. 

Numerous  F3  plants  of  the  several  color  types  of  the  cross  under  con- 
sideration here  were  tested  by  F4  and  F5  progenies,  with  results  wholly 
consistent  with  expectation.  It  is  deemed  unnecessary  to  give  the  records 
of  these  later  generations  in  detail. 

Evidence  from  aleurone-color  and  linkage  relations 
The  evidence  presented  up  to  this  point  in  support  of  the  three-factor 
hypothesis,  involving  A  a,  Bh,  PI  pi,  has  had  to  do  .with  the  behavior 
of  the  several  F2  color  types  in  later  generations  and  in  intercrosses. 
There  remain  to  be  discassed  some  bits  of  evidence  which,  while  less  direct, 
are  perhaps  no  less  trustworthy.  This  evidence  deals  with  (1)  the  relation 
of  aleurone  color  to  plant-color  types,  (2)  the  linkage  of  certain  plant-color 
types  with  endosperm  color,  and  (3)  the  Hnkage  of  other  color  types 
with  the  liguleless  leaf. 

Relation  of  aleurone  color  to  plant  color. —  Of  the  plant-color  factors 
considered  in  this  section  of  the  paper,  the  pair  A  a  is  concerned  also 
in  the  development  of  alem'one  color.     It  has  been  shown  by  the  writer 


Plant  Colors  in  Maize  ,  59 

ill  a  previous  paper  (Emerson,  1918)  that  the  presence  of  three  dominant 
factorS;  A,  C,  and  R,  is  necessary  for  the  development  of  aleurone  color. 
It  is  assumed  that  the  factor  pair  A.a  for  aleurone  color  is  identical  with  the 
pair  A  a  for  plant  color.  Some  of  the  evidence  on  which  this  assumption 
is  based  may  well  be  considered  at  this  point  in  order  to  justify  the 
use  of  the  same  symbols  for  both  plant  and  aleurone  color.  After  the 
identity  oi  Aa  has  been  estal)lished,  certain  relations  of  aleurone  color 
to  plant  color  can  be  used  to  check  up  some  of  the  conclusions  previously 
drawn  with  respect  to  the  genetic  interrelations  of  the  several  plant-color 
types. 

It  will  be  recalled  that  dilute  sun  red  crossed  with  green  gave  dilute 
sun  red  in  Fi  and  a  3:1  ratio  of  the  two  types  in  F2  (table  17,  group  1, 
page  134),  and  that  backcrosses  of  Fi  with  green  gave  a  1 : 1  ratio  (group  2). 
The  F2  seeds  of  these  Fi  plants  also  exhibited  a  3: 1  relation  —  424  colored 
and  127  colorless,  deviation  10.8  ±  6.9  —  thus  showing  that  only  one 
factor  pair,  A  a,  C  c,  or  R  r,  was  heterozygous.  The  colorless  seeds 
produced  98  green  plants,  and  the  colored  ones  produced  269  dilute  sun 
reds  and  1  weak  plant,  recorded  as  green,  which  died  in  the  seedling 
stage.  Obviously  the  factor  that  differentiates  dilute  sun  red  from  green 
is  the  same  as  the  one  that  in  these  cases  differentiated  the  colored  from 
the  colorless  seeds,  or  some  factor  very  closely  linked  with  it.  Fortunately, 
Fi  plants  closely  related  to  the  ones  which  when  selfed  showed  the  behavior 
noted  above,  were  backcrossed  with  green,  colorless-seeded  A  testers 
(Emerson,  1918).  Of  the  resulting  seeds  632  were  colored  and  590  were 
colorless,  evidently  a  1:1  relation  —  the  deviation  being  21  ±  11.8  — 
showing  that  the  Fi  plants  were,  with  respect  to  aleurone  color,  A  a 
C  C  R  R.  The  colored  seeds  gave  rise  to  357  dilute  sun  red  plants  and 
the  colorless  seeds  to  358  green  plants.  Evidently,  therefore,  it  is  the 
Aa  pair  that  differentiates  dilute  sun  red  from  green.  This  is  in  support 
of  the  assumed  genotypes  A  h  pi  and  a  b  pi  for  dilute  sun  red  and  green, 
x^spectivel}'. 

The  single  progeny  recorded  in  group  3  of  table  9  (page  127)  came 
from  a  plant  known  to  be  A  a  with  respect  to  aleurone  color  and  pro- 
ducing 130  colored  and  41  colorless  seeds.  The  3:1  aleurone-color  relation 
shows  it  to  have  been  heterozygous  in  only  one  aleurone-color  factor, 
and  therefore  AaCCRR.  The  colored  seeds,  ACR,  produced  67 
purple  plants,  and  the  colorless  ones,  aC  R,  produced  21  brown  plants. 


60  R.  A.  Emerson 

Evidently,  purples  are  differentiated  from  browns  by  the  A  a  pair  alone, 
just  as  dilute  sun  reds  are  differentiated  from  greens.  This  is  quite 
in  keeping  with  the  assmned  genotypes,  A  B  PI  and  a  B  PI,  for  purple 
and  brown,  respectively. 

Two  of  the  progenies  recorded  in  group  3  of  table  8  (page  126)  involved 
both  aleurone  and  plant  color.  The  heterozygous  parents  were  back- 
crossed  with  green  A  testers  and  produced  125  colored  and  127  colorless 
seeds.  The  factor  pair  differentiating  these  two  seed  classes  was  therefore 
Aa.  The  colored  seeds,  A  C  R,  produced  15  purple  and  14  sun  red  plants, 
while  the  colorless  seeds,  aC  R,  gave  9  brown  and  14  green  plants.  Since 
it  is  shown  in  the  preceding  paragraph  that  purples  and  browns  differ 
with  respect  to  the  pair  A  a  alone,  it  may  be  inferred  that  the  sun  reds 
and  the  greens  of  these  lots  also  differed  with  respect  to  A  a  alone.  The 
assumption  heretofore  made  with  respect  to  the  genotypes  of  these  color 
classes,  A  B  PI,  A  B  pi,  a  B  PI,  and  a  B  pi,  for  pm"ple,  sun  red,  brown, 
and  green,  respectively,  is  given  support  by  this  relation  of  aleurone 
color  to  plant  color. 

Two  of  the  progenies  recorded  in  group  1  of  table  9  (page  127),  and  one 
in  group  4  of  table  8  (page  126),  were  grown  from  self-polhnated  plants 
known  to  be  A  a  with  respect  to  aleurone  color  and  found  to  have  644 
colored  and  228  colorless  seeds.  The  3 : 1  seed-color  relation  shows  them 
to  have  been  AaC C RR.  The  colored  seeds,  A  C  R,  gave  294  purples 
and  113  dilute  purples,  while  the  colorless  seeds,  aC  R,  gave  119  browns 
and  40  greens.  If  purples  and  brov/ns  differ  with  respect  to  A  a  alone, 
as  they  have  been  shown  to  do,  presumably  the  dilute  purples  and  the 
greens  of  these  lots  also  differ  in  the  same  way.  This  is  in  keeping  with 
the  assumption  that  the  genotypes  of  the  color  classes  are  A  B  PI,  A  b  PI, 
a  B  PI,  and  a  bPl,  for  purple,  dilute  purple,  brown,  and  green,  respectively. 

These  comparisons  of  the  relations  of  aleurone  color  to  plant  color  have 
confirmed  definitely  the  supposition  that  purples,  sun  reds,  dilute  purples, 
and  dilute  sun  reds  have  the  dominant  factor  A,  and  browns  and  greens 
the  recessive  factor  a.  The  comparisons  have  also  afforded  some  support 
for  the  assumed  genetic  constitution  of  the  several  color  types  with  regard 
to  B  b  and  PI  pi.  More  definite  evidence  for"  the  latter,  however,  is 
afforded  by  the  linkage  relations  now  to  be  discussed. 

Liyikage  of  plant  color  with  endosperm  color. —  It  has  been  known  since 
1942  that  a  Unkage  exists  between  the  factor  pau*  PI  pi  and  endosperm 


Plant  Colors  in  Maize  61 

color.  The  data  siigsost  irregularities  or  complexities  which  cannot  be 
straightened  out  until  more  definite  information  is  at  hand  with  regard 
to  the  two  or  more  factor  pairs  concerned  in  the  development  of  yellow 
endosperm.^  Only  such  data  are  presented  here  as  are  necessary  to 
show  the  relations  of  the  several  plant-color  types  to  endosperm  color, 
f  A  single  progeny  recorded  in  table  27,  group  2  (page  140),  was  made 
up  of  74  purple  and  75  sun  red  plants.  The  lot  resulted  from  a  cross 
of  a  white-seeded  sun  red  plant  with  a  dilute  purple  plant  which  was 
heteroz3'-gous  with  respect  to  both  yellow  endosperm  and  plant  color.  The 
j^ellow  seeds  produced  58  purple  and  20  sun  red  plants,  and  the  white 
seeds  produced  16  purple  and  55  sun  red  plants.  The  yellow-seeded 
sun  reds  and  the  white-seeded  dilute  purples  are  known  to  be  the  crossover 
classes.  The  ratio  of  non-crossovers  to  crossoveis  is  113:36,  and  the 
percentage  of  crossing-over,  therefore,  is  24.2.  Evidently  a  factor  pair  for 
yellow  endosperm,  Y  y,  is  linked  with  the  factor  pair  that  differentiates 
purple  from  sun  red.  In  accordance  with  the  hypothesis  under  test,  this 
plant-color  factor  pair  is  PI  pi  —  purple  =  ABPl,  and  sun  red  =  ABpl. 
Two  other  progenies  (table  26,  group  1,  page  139)  had  a  total  of  116 
dilute  purple  and  42  dilute  sun  red  plants.  The  selfed  parent  plants 
were  heterozj^gous  for  yellow  endosperm  as  well  as  for  plant  color.  The 
yellow  seeds  gave  99  dilute  purple  and  17  dilute  sun  red  plants,  and  the 
white  seeds  gave  17  dilute  purple  and  25  dilute  sun  rod  plants.  This 
F2  distribution,  as  shown  below,  is  very  close  to  expectation  ( z^  =  0.26) 
on  the  basis  of  25  per  cent  of  crossing-ovei  between  the  factor  pair  Yy 
and  the  pair  that  differentiates  dilute  purple  from  dilute  sun  red.  It  seems 
likel}^  therefore,  that  the  same  plant-color  factors,  PI  pi,  are  concerned 
here  as  in  the  progeny  consisting  of  purples  and  sun  reds.  This  is  in 
keeping  with  the  theoretical  genotypes,  A  b  PI  and  A  b  pi.  assmned  for 
dilute  purple  and  dilute  sun  red,  respectively.  The  comparison  between 
the  observed  Fo  distribution  and  that  calculated  on  the  basis  of  25  per 
cent  of  crossing-over  follows: 

Observed 99  17  17  25   =     158 

Calculated,  y 102  17  17  23   =      159 

Difference —3  0  0  +2  —1 

'  This  problem  is  being  investigated  by  Dr.  E.  G.  Anderson. 


62  R.  A.  Emerson 

A  single  progeny  (table  8,  group  3,  page  126)  from  a  selfed  parent 
heterozygous  for  yellow  endosperm,  contained  purple,  sun  red,  brown, 
and  green  plants,  totaling  63,  in  the  relation  35:15:6:7.  These  four 
color  types  are  expected  to  occur  in  a  total  of  64  in  the  relation  36: 12: 12:4 
from  a  selfed  plant  of  the  genotype  AaB B  Plpl.  The  observed  deviation 
from  expectation  might  occur  by  chance  once  in  nine  trials,  P  equaling 
0.11.  Theoretically,  the  green  plants  of  this  lot,  aB  pi,  are  differentiated 
from  the  browns,  a  B  PI,  by  the  same  factor  pair,  Plpl,  that  differentiates 
the  sun  reds,  A  B  pi,  from  the  purples,  A  B  PI.  If  this  is  true,  the 
same  linkage  relations  should  exist  for  yellow  endosperm  with  the 
brown-green  lot  as  with  the  purple-sun-red  lot.  From  yellow  seeds  there 
came  29  purples  and  8  sun  reds,  and  from  white  seeds  6  purples  and  7 
sun  reds.  Such  a  distribution  should  be  very  closely  realized  (  /.^  =  0.97) 
from  30  per  cent  crossing-over  between  Y  y  and  PI  pl.  The  yellow  seeds 
produced  also  5  brown  and  3  green  plants,  and  the  white  seeds  1  brown 
and  4  green  plants.  While  the  number  of  individuals  is  too  small  to  give 
a  reliable  indication,  it  is  of  interest  to  note  that  the  coefficient  of  asso- 
ciation (Collins,  1912)  calculated  from  the  series  5:3:1:4,  or  0.739,  is 
practically  that  calculated  from  26  per  cent  of  crossing-over.  In  so  fai" 
as  these  records  go,  therefore,  they  support  the  assumption  that  brown 
and  green  in  this  lot  are  differentiated  by  the  same  factor  pair  as  are 
purple  and  sun  red,  and  thereby  support  the  hypothesis  under  test. 

A  plant  heterozygous  for  the  three  plant-color  pairs  A  a,  B  b,  PI  pl, 
and  for  Yy,  backcrossed  with  a  white-seeded  green  plant  of  type  Vic, 
a  h  pl  y,  gave  the  six  color  types,  purple,  sun  red,  dilute  purple,  dilute 
sun  red,  brown,  and  green,  in  the  numerical  relation  10:13:17:11:9:33 
(ta])le  6,  page  124),  which  is  a  close  fit  (P  =  0.61)  to  the  expected  relation, 
1:1:1:1:1:3.  From  yellow  seeds  the  resulting  series  was  8:6:13:2:7  :.17, 
and  from  white  seeds  it  was  2:7:4:9:2:16.  When  the  classes  having 
A  Pl,  purple  and  dilute  purple,  were  lumped  together,  and  similarly 
those  having  A  pl,  sun  red  and  dilute  sun  red,  the  yellow  seeds  gave  21 
plants  wifh  Pl  and  8  with  pl,  while  the  white  seeds  gave  6  with  Pl  and 
16  with  pl.  Of  these  51  plants,  there  were  14  in  the  crossover  classes, 
or  a  percentage  of  crossing-over  of  about  27.5  ±4.1,  approximately  the 
same  as  in  the  cases  cited  above.  In  this  lot  there  are  theoretically  three 
kinds  of  greens,  a  B  pl,  ah  Pl,  and  a  h  pl,  one  of  which  has  Pl  and  two 
of  which  have  pl,  while  all  the  browns,  a  B  Pl,  have   Pl.     If  there  be 


Plant  Colors  in  Maize  63 

assumed  25  per  cent  of  crossing-over  between  Fy  and  PI  pi,  equivalent 

to  a  3:1:1:3  gametic  series,  yellow  seeds  should  give  3  brown  to  5  green, 
and  white  seeds  1  brown  to  7  green,  as  shown  below: 

Yellow  White 

Brown,  a  B  PI 3  1 

Green,  a  B  pi 1  3 

Green,  ab  PI 3  1 

Green,  abpl 1  3 


The  yellow  seeds  actually  gave  7  brown  to  17  green  and  the  white  seeds 
2  brown  to  16  green,  which  is  a  close  fit  to  the  calculated  relation,  3:5: 
1:7  (P  =  0.59).  In  this  case  as  in  the  others,  then,  the  linkage  relations 
between  Y  y  and  PI  pl  afford  additional  support  for  the  belief  that  the 
several  color  types  actually  bear  to  one  another  the  relation  assumed  in 
the  assignment  of  hypothetical  genetic  formulae  (page  32). 

Linkage  of  plant  color  icith  leaf  type. —  It  has  been  known  for  some 
years  that  a  leaf  type  termed  liguleless  (Emerson,  1912)  is  linked  with 
the  factor  pair  that  differentiates  sun  red  from  dilute  sun  red.  As  an 
illustration  of  this,  two  backcross  progenies,  8250  and  8253,  with  a  total 
of  145  sun  red  and  147  dilute  sun  red  plants,  may  be  cited.  These  progenies 
came  from  a  cross  of  normal-leaved  sun  red,  A  B  pl  Lg,  with  liguleless- 
leaved  dilute  sun  red,  A  b  pl  lg,  backcrossed  with  liguleless  dilute  sun  red. 
Of  the  normal-leaved  plants  104  were  sun  red  and  41  were  dilute  sun  red, 
while  of  the  liguleless-leaved  plants  48  were  sun  red  and  99  were  dilute 
sun  red.  The  non-crossovers  were  to  the  crossovers  as  203:89,  or  a  per- 
centage of  crossing-over  of  30.5.  Since  the  factor  pair  that  differentiates 
sun  red  from  dilute  sun  red  has  been  assigned  the  symbol  B  b,  the  linkage 
noted  here  is  evidently  between  B  b  and  Lg  lg. 

Six  progenies  from  backcrosses  of  heterozygous  normal-leaved  purples 
with  liguleless  dilute  sun  reds  gave  purples,  sun  reds,  dilute  purples,  and 
dilute  sun  reds  in  the  relation  197:177:178:167,  which  is  not  far  from  the 
equality  expected,  P  equaling  0.46.  Among  the  normal-leaved  plants, 
the  four  color  types  occurred  in  the  relation  123:117:47:55,  and  among 
the  liguleless-leaved  plants  in  the  relation  74:60: 131: 112.  Evidently  the 
purples  bear  the  same  relation  to  the  dilute  purples  as  the  sun  reds  do  to 
3 


64  R.  A.  Emerson 

the  dilute  sun  reds.  For  sun  reds  and  dilute  sun  reds,  the  non-crossovers 
are  to  the  crossovers  as  229:115,  or  a  crossover  percentage  of  33.4  ±  1.7. 
For  purples  and  dilute  purples,  the  relation  is  254:121,  or  a  crossover 
percentage  of  32.3  ±  1.5.  It  follows  from  this  that  the  factor  pair,  B  h, 
which  differentiates  sun  red,  A  B  -pi,  from  dilute  sun  red,  A  b  pi,  is  the 
same  as  that  which  differentiates  purple  from  dilute  purple.  And  this 
is  in  keeping  with  the  hypothesis  under  test,  in  accordance  with  which 
purple  and  dilute  purple  have  been  assigned  the  genotypes  A  B  PI  and 
A  b  PI,  respectively. 

In  a  single  progeny  resulting  from  a  backcross  of  a  heterozygous  normal- 
leaved  purple  plant  with  a  liguleless-leaved  green  plant,  greens  occurred, 
as  expected,  with  about  three  times  the  frequency  of  the  average  of 
the  other  five  color  classes.  The  progeny  included  14  browns  and  49 
greens.  Of  the  normal-leaved  plants  there  were  10  browns  and  19  greens, 
and  of  the  liguleless-leaved  plants  4  browns  and  30  greens.  On  the  basis 
of  the  hypothetical  genotypes  assigned  to  browns  and  greens,  and  with 
the  assumption  of  33  per  cent  of  crossing-over  between  B  b  and  Lg  Ig, 
the  four  classes,  normal  brown,  normal  green,  liguleless  brown,  and 
hguleless  green,  should  bear  the  relation  2:4:1:5.  For  a  total  of  63 
plants,  the  relation  would  be  approximately  11:21:5:26,  whereas  the 
observed  relation  was  10:19:4:30.  The  deviations  from  expectation  are 
such  as  might  occur  by  chance  in  more  than  three  out  of  four  trials,  P 
equaling  0.78.  In  this  case,  as  in  the  others  reported,  the  linkage  relations 
between  B  b  and  Lg  lg  afford  support  for  the  view  that  the  several  color 
types  bear  the  relation  to  one  another  inferred  from  the  hypothetical 
genotypes  assigned  them. 

Summary  of  results  involving  A  a,  Bb,  PI  pi 

The  results  of  the  cross  of  purple  with  green  —  which  gave  in  F2  six 
color  types,  namely,  purple,  sun  red,  dilute  purple,  dilute  sun  red,  brown, 
and  green,  with  a  numerical  relation  of  approximately  27:9:9:3:9:7 
from  selfed  Fi's  and  about  1:1:1:1:1:3  from  Fi's  backcrossed  to  green  — 
have  been  interpreted  on  the  basis  of  the  interaction  of  three  factor  pairs, 
A  a,  Bb,  and  PI  pl.  This  hypothesis  has  been  subjected  to  practically 
every  genetic  test  available,  as  summarized  below. 

Each  of  the  six  Fo  color  types  has  in  turn  been  tested  by  its  behavior 
in  F3,  and  in  several  cases  behavior  in  F4  and  even  in  later  'generations 


Plant  Colors  in  Maize  65 

has  been  noted.  All  the  possible  combinations  of  intercrosses  between 
the  several  types  have  been  studied,  except  dilute  purple  x  brown.  In 
most  cases  these  intercrosses  have  been  carried  to  the  F2  generation, 
and  in  several  instances  to  F3  and  F4.  Thruout  the  tests,  the  results 
have  been  in  close  agreement  with  those  expected  from  the  hypothesis. 
In  almost  every  instance  all  the  color  types  expected  in  each  generation 
of  the  several  crosses,  and  no  others,  have  appeared.  Moreover,  the 
numerical  relations  found  to  exist  between  the  several  color  types  and  also 
between  the  several  classes  of  behavior  have  been  reasonably  close  to 
expectation.  It  is  true  that  in  some  instances  the  fit  of  observation 
to  hypothesis  has  not  been  particularly  good,  but  even  here  the  observed 
deviations  have  been  of  such  an  order  as  might  be  expected  to  occur 
occasionall}^  thru  the  chance  errors  of  random  sampling. 

In  addition  to  the  tests  afforded  by  the  behavior  of  the  several  Fj 
color  types  in  later  generations  and  in  intercrosses,  the  relations  of  aleurone 
color  involving  the  factor  pair  A  a  to  tlie  several  plant  colors,  and  the 
linkage  relations  of  the  plant-color  factors  PI  pi  with  the  endosperm-color 
factors  Y  ij  and  of  the  plant-color  factors  B  h  with  the  leaf-type  factors 
Lg  Ig,  have  been  included  in  the  investigation.  These  tests  have  shown 
that  the  several  color  types  bear  to  one  another  the  relations  to  be  deduced 
from  the  hypothetical  genotypes  assigned  them. 

The  conclusion  seems  justified,  therefore,  that  the  three-factor  hypoth- 
esis proposed  as  an  interpretation  of  the  F2  results  obtained  in  crosses 
of  purple  with  green  has  been  substantiated,  in  so  far  as  it  is  possible 
to  substantiate  any  hypothesis. 

CROSSES   INVOLVING   THE   MULTIPLE   ALLELOMORPHS   B,   B'^ ,  b\  b 

In  the  preceding  section  of  this  account,  six  color  phenot3'pes  of  maize 
have  been  discussed,  namely,  purple,  sun  red,  dilute  purple,  dilute  sun 
red,  brown,  and  green.  In  addition  to  these  six  phenotypes,  green  plants 
have  been  shown  to  consist  of  three  genotypes,  which  in  some  instances 
are  slightly  different  phenotypically.  Besides  these  six  sharply  separable 
phenotypes,  there  exist  certain  intermediate  forms.  The  constancy 
of  the.se  types  from  year  to  year,  under  fairly  uniform  environmental 
conditions,  leaves  no  doubt  that  they  are  genotypically  as  well  as  pheno- 
typically distinct  from  the  types  considered  heretofore. 


66  R   A.  Emerson 

One  of  these  forms,  known  as  weak  purple,  type  lb,  is  intermediate 
in  certain  respects  between  purple  and  sun  red,  and  in  other  respects 
between  purple  and  dilute  purple.  Plants  of  this  type,  prior  to  the 
flowering  stage,  frequently  resemble  sun  reds  more  than  purples.  The 
pigmentation  of  the  sheaths  is  less  intense  than  with  purples,  and  in 
some  instances  less  than  with  strong  sun  reds.  There  is,  however,  sooner 
or  later  a  tendency  for  pigment  to  develop  on  the  stalk  beneath  the 
sheaths  (Plate  V,  2) ,  In  this  respect  weak  purples  resemble  dilute  purples 
as  the  latter  often  appear  in  a'  late  stage  of  their  development.  The 
anthers  of  weak  purples  are  usually  full  purple,  like  those  of  purples 
and  dilute  purples,  in  which  respect  they  show  no  resemblance  to  sun  reds. 

A  second  intermediate  form,  known  as  weak  sun  red,  type  lib,  stands 
between  sun  red  and  dilute  sun  red.  The  sheaths  and  husks  are  less 
extensively  and  less  intensely  pigmented  than  is  true  of  full  sun  red,  and 
yet  exhibit  much  more  color  than  in  dilute  sun  red  (Plate  V,  4).  The 
anther  color  of  weak  sun  red  is  like  that  of  both  sun  red  and  dilute  sun 
red. 

While  the  difference  between  the  extreme  sun-color  types,  sun  red  and 
dilute  sun  red,  is  probably  only  a  quantitative  one  —  as  is  also  presumably 
true  of  the  difference  between  purple  and  dilute  purple  —  little  difficulty 
is  experienced  in  separating  sun  red  from  dilute  sun  red  plants  on  the  one 
hand,  or  purple  from  dilute  purple  plants  on  the  other.  Frequently, 
however,  it  is  difficult,  or  even  impossible,  at  early  stages  of  plant  growth, 
to  separate  sun  reds  from  purples.  The  existence  of  such  intermediate 
forms  as  weak  purple  and  weak  sun  red  adds  materially  to  the  difficulties 
of  classification.  In  fact,  correct  classification  of  all  these  types  by  inspec- 
tion alone  is  possible  only  at  the  flowering  stage.  For  certainty  in  classi- 
fication, even  at  the  flowering  stage,  environmental  conditions,  particularly 
soil  fertility,  must  have  been  favorable  thruout  the  growing  period  of  the 
plants.  While  infertile  soil  exaggerates  the  difference  between  dilute 
sun  red  and  green,  by  bringing  about  an  excessive  development  of  red 
■  pigment  in  the  one  type  while  no  color  develops  in  the  other,  on  fertile  soil 
only  are  revealed  the  finer  distinctions  between  sun  red,  weak  sun  red, 
and  dilute  sun  red.  It  is  perhaps  fortunate  that  the  genetic  relations  of 
these  several  types  are  such  that  ordinarily  not  all  of  them  occur  in  a 
single  progeny. 


Plant  Colors  in  Maize  67 

Interrelations  of  sun  red  Ila,  weak  sun  red  lib,  and  dilute  sun  red  IVa 

Numerous  crosses  of  weak  sun  reds,  lib,  with  dilute  sun  reds,  IVa, 
have  given  weak  sun  reds  in  Fi  and  approximately  three  weak  sun  reds 
to  one  dilute  sun  red  in  F2,  just  as  crosses  of  strong  sun  red  with  dilute 
sun  red  give  three  strong  to  one  dilute  sun  red  (table  24,  group  1,  page  138). 
Records  of  such  crosses  are  given  in  table  32  (page  144).  Twelve  F2 
progenies,  totaling  1729  individuals,  showed  the  two  types  in  the  relation 
1300:429,  almost  exactly  a  3:1  ratio,  the  deviation  being  3.3  ±  12.1. 
The  data  for  F3  of  these  crosses  are  like  those  for  crosses  of  strong  sun  red 
with  dilute  sun  red  (table  25).  One  weak  sun  red  F2  bred  true  in  F3 
with  a  total  of  77  weak  sun  red  offspring  (table  33,  group  1).  Four  others 
gave  both  weak  and  dilute  sun  reds  (group  2),  in  the  relation  128:54,  a 
deviation  of  8.5  ±  3.9  from  a  3:1  ratio.  One  dilute  sun  red  bred  true 
(group  3),  with  95  dilute  sun  red  plants  in  F3. 

A  cross  of  weak  sun  red,  lib,  with  strong  sun  red,  Ila,  gave  strong  sun 
red  in  Fi  and  the  two  parent  types  in  F2  in  the  relation  71 :  16,  a  deviation 
from  the  3: 1  ratio  of  5.75  ±  2.72.  There  is,  therefore,  nearly  one  chance 
in  six  that  the  observed  deviation  may  be  due  to  errors  of  random  sampling, 
P  equaling  0.16. 

In  none  of  these  crosses,  strong  with  weak,  weak  with  dilute,  and  strong 
with  dilute  sun  red,  have  other  than  the  parent  types  appeared  in  F2. 
If  weak  sun  red  is  due  to  the  action  of  some  additional  modifying  factor, 
not  heretofore  considered,  types  other  than  those  of  the  parents  should 
have  occurred  in  some  of  the  crosses.  The  natural  conclusion,  therefore, 
is  that  weak  sun  red,  lib,  is  due  to  an  allelomorph  of  B  and  b,  the  pair 
concerned  with  the  difference  between  sun  red,  I  la,  and  dilute  sun  red, 
IVa.  This  third  allelomorph,  responsible  for  weak  sun  red,  may  well  be 
designated  B^. 

Further  evidence  in  support  of  the  assumption  that  an  allelomorph  of 
B  and  b  is  concerned  with  weak  sun  red  is  afforded  by  linkage  studies 
involving  strong,  weak,  and  dilute  sun  red  with  loaf  type.  Evidence  has 
been  offered  (page  63)  to  show  that  B  b  and  Lg  Ig  are  linked  with  about 
30  to  33  per  cent  of  crossing-over. 

A  single  progeny,  8252,  from  a  sun  hkI  plant  heterozygous  for  leaf  type 
and  plant  color  backcro.ssed  to  liguleless  weak  sun  red,  contained  108 
sun  red  and  109  weak  sun  red  plants.     Of  the  normal-leaved  plants  80 


68  R-  A.  Emekson 

were  sun  red  and  38  were  weak  sun  red,  while  of  the  Hguleless-leaved  plants 
28  were  sun  red  and  71  were  weak  sun  red.  The  ratio  of  non-crossovers 
to  crossovers  is  151:66,  or  30.4  ±  2.1  per  cent  of  crossing-over.  The 
percentage  of  crossing-over  between  Lg  Ig  and  the  factor  pair  differentiating 
sun  red  and  weak  sun  red,  B  B"",  is,  therefore,  practically  the  same  as  the 
linkage  between  Lg  lg  and  B  b. 

Four  backcross  progenies,  8246-8249,  involving  sun  red,  contained  469 
weak  sun  red  and  396  dilute  sun  red  plants.  Of  the  normal-leaved  plants 
153  were  weak  sun  red  and  261  were  dilute  sun  red,  while  of  the  liguleless- 
leaved  plants  316  were  weak  sun  red  and  135  were  dilute  sun  red.  The 
non-crossovers  are  to  the  crossovers  as  577:288,  or  33.3  ±1.1  per  cent  of 
crossing-over.  Here  again,  therefore,  the  linkage  between  Lg  lg  and  the 
factor  pair  differentiating  weak  sun  red  from  dilute  sun  red,  B^  b,  is 
practically  the  same  as  that  between  Lg  lg  and  B  b  or  between  Lg  lg  and 
BB"". 

From  the  facts  (1)  that  in  crosses  between  any  two  of  the  three  types 
sun  red,  weak  sun  red,  and  dilute  sun  red,  the  third  type  is  not  produced, 
and  (2)  that  the  linkage  value  between  Lg  lg  and  the  factor  pairs  differen- 
tiating weak  sun  red  from  sun  red  and  from  dilute  sun  red  is  approxi- 
mately the  same  as  that  between  Lg  ly  and  B  b,  it  seems  evident  that  weak 
sun  red  is  due  to  a  factor  B^  belonging  to  the  triple  allelomorphic  series 
B,  5"',  b. 

It  seems  probable  that  this  series  of  allelomorphs  contains  other  members 
in  addition  to  the  three  listed  above,  but  there  is  at  present  little  conclu- 
sive evidence  in  support  of  the  idea.  There  are  certainly  several  forms, 
commonly  classed  as  dilute  sun  red,  that  differ  considerably  in  the  amount 
of  red  pigment  developed,  and  certainly  some  of  these  differences  are 
genetic.  As  is  shown  in  the  next  section  of  this  account,  some  of  these 
differences,  particularly  with  respect  to  silk,  anther,  and  leaf-blade  color, 
are  due  to  the  effect  of  the  aleurone-color  factors  R  r.  Environmental 
conditions,  particularly  soil  fertility,  influence  the  development  of  this 
pigment  so  greatly  that  the  prol^lem  becomes  a  difficult  one.  There  is, 
however,  some  evidence  that  at  least  two  forms  of  dilute  sun  red  are 
differentiated  by  a  factor  pair  belonging  to  the  series  B,  B^,  b.  These 
forms  differ  principally  in  the  amount  of  color  in  the  fresh  husks  (Plate 
VI,  1  and  2),  and  to  some  extent  in  the  sheaths,  which  arc  the  plant  parts 
most  strikingly  different  in  sun  red,  weak  sun  red,  and  dilute  sun  red. 


Plant  Colors  in  Maize  69 

A  type  of  dilute  sun  red  with  stronger  husk  pigmentation  than  ordinary 
dikite  sun  red  shows  was  crossed  with  an  ordinary  dihite  purple.  Leaf 
type  also  was  involved  in  the  cross.  The  Fi  plants  were  dilute  purples 
with  somewhat  more  pigment  in  the  husks  of  young  ears  than  is  usual 
with  that  type.  A  single  progeny,  grown  from  an  Fi  backcrossed  with 
liguleless  dilute  sun  red  of  a  light  type,  consisted  of  25  dilute  purples  and 
18  dilute  sun  reds.  Each  of  these  classes  was  sorted  with  some  difficulty 
into  light  and  more  strongly  colored  subclasses,  in  accordance  with  the 
amount  of  color  on  the  husks  of  the  young  ears.  Of  the  more  strongly 
pigmented  dilute  sun  reds  4  had  normal  and  6  had  liguleless  leaves,  while  of 
the  lighter  dilute  sun  rods  6  had  normal  and  2  had  liguleless  leaves.  Of  the 
more  strongly  colored  dilute  purples  4  had  normal  and  13  had  liguleless  leaves, 
while  of  the  lighter  ones  4  had  normal  and  4  had  liguleless  leaves.  While 
these  numbers  are  small  and  the  behavior  was  somewhat  irregular,  it  is 
perhaps  noteworthy  that  the  factor  pair  differentiating  the  lighter  from 
the  more  strongly  colored  plants,  of  both  the  dilute  sun  red  and  the  dilute 
purple  classes,  exhibited  an  apparent  linkage  with  Lq  Ig  of  a  value  not 
far  from  that  observed  between  Lg  Ig  and  B  b,  B  B^,  and  B^  b.  The 
observed  percentages  of  crossing-over  were  32.0  for  the  dilute  purples, 
33.3  for  the  dilute  sun  reds,  and  32.6  for  the  entire  lot.  This  evidence, 
slight  as  it  is,  plainly  suggests  a  fourth  member,  b%  of  the  B  series  of 
allelomorphs,  which  may  be  stated  tentatively  as  B,  B^,  6*,  b. 

Relation  of  weak  purple  lb  to  purple  la,  dilute  purple  Ilia,  and  weak  sun 

red  lib 
By  methods  similar  in  the  main  to  those  outlined  above,  Dr.  E.  O. 
Anderson  has  been  able  to  show  that  weak  purple  is  differentiated  from 
purple  on  the  one  hand  and  from  dilute  purple  on  the  other  by  the  same 
factor,  B^,  that  differentiates  weak  sun  red  from  sun  rod  and  from  dilute 
sun  red.  At  the  time  when  Dr.  Anderson  undertook  to  determine  the 
genetic  relations  of  weak  purple,  nothing  was  known  of  the  relation  of 
weak  sun  red  to  sun  red  and  dilute  sun  rod  as  presented  above.  Further- 
more, there  was  no  indication  as  to  whether  weak  purple  was  dififerentiated 
from  purple  and  dilute  purple  by  an  allelomorph  of  /^  6  or  of  PI  pi,  or  by 
some  distinct  factor  pair  that  might  modify  the  ordinary  result  of  the 
interaction  of  the  pairs  A  a,  B  h,  and  PI  pi  then  known  to  be  concerned 
in  the  production  of  plant  colors.     The  evidence  to  be  presented  here 


70  R-  A.  Emerson 

is  taken  almost  wholly  from  Dr.  Anderson's  records,  and  the  conclusions 
derived  from  it  are  his.  It  is  with  Dr.  Anderson's  permission  and  at 
his  suggestion  that,  for  the  sake  of  completeness  of  this  account  of  the 
inheritance  of  plant  colors,  his  results  are  here  presented. 

A  cross  of  a  weak  purple  lb  with  a  homozygous  dilute  purple  Ilia 
resulted  in  25  weak  purples  only,  while  a  cross  of  another  weak  purple 
with  a  homozygous  dilute  purple,  a  sib  of  the  plant  used  in  the  first  cross, 
gave  63  weak  purples  and  53  dilute  purples.  Two  of  the  Fi  weak  purples 
were  backcrossed  to  dilute  purples,  and  a  third  to  dilute  sun  red.  The 
result  (table  34,  group  1,  page  145)  was  141  weak  purples  and  163  dilute 
purples,  a  deviation  of  11  ±5.9  from  equality.'  Five  crosses  of  weak 
purples  with  dilute  sun  reds  gave  a  total  of  32  weak  purples  and  25  dilute 
purples,  a  deviation  from  equality  of  3.5  ±  2.5,  while  two  other  such 
crosses  gave  29  weak  purples  only.  Evidently  these  weak  purple  plants 
differed  from  dilute  purples  by  a  single  factor  pair.  This  pair  could  not 
have  been  PI  pi,  for  the  crosses  of  weak  purple  with  dilute  purple,  A  b  PI, 
gave  the  same  results  as  those  with  dilute  sun  red,  Ab  pi.  This  leaves  the 
■possibility  that  B  b  or  some  unknown  factor  pair  was  concerned. 

Three  crosses  of  weak  purple  lb  with  purple  la  resulted  in  52  purple 
plants.  A  single  cross  of  weak  purple  with  sun  red  Ila  gave  18  purples. 
Evidently  both  purple  and  sun  red  carry  some  factor  that  acts  to  change 
weak  purple  fco  purple.  Unfortunately,  no  later  generations  of  any  of 
these  crosses  were  grown,  but  it  is  evident  from  the  Fi  results  and  from 
what  is  known  of  the  interrelations  of  purple,  sun  red,  and  dilute  purple 
that  the  dominant  factor  B,  common  to  both  purple  and  sun  red,  is  con- 
cerned in  the  change  from  weak  purple  to  purple.  Since  the  crosses  of 
weak  purple  with  dilute  purple,  A  b  PI,  and  with  dilute  sun  red,  A  b  pi, 
gave  no  purples,  while  crosses  of  weak  purple  with  purple,  A  B  PI,  and 
with  sun  red,  A  B  pi,  gave  purple,  the  Pljjl  pair  is  not  concerned  in  the 
difference  between  weak  purple  and  purple  any  more  than  in  that  between 
weak  purple  and  dilute  purple.  These  results,  however,  do  not  exclude 
the  possibility  that  weak  purple  may  be  Ab  PI,  like  dilute  purple,  with 
the  addition  of  some  unknown  dominant  modifying  factor. 

A  single  weak  purple  plant,  which  was,  so  far  as  known,  imrelated  to 
the  weak  purples  considered  above,  when  crossed  with  two  unrelated 
dilute  sun  reds  gave  progenies  consisting  of  15  weak  purples  and  13  weak 
sun  reds.     Seven  progenies  of  these  Fi  weak  purple  plants  backcrossed 


Weak 

Dilute 

Dilute 

T'^  +  r.l 

sun  red 

purple 

sun  red 

iotai 

lib 

Ilia 

IVa 

526 

460 

537 

2,004 

501 

501 

501 

2,004 

Plant  Colors  ix  Maize  71 

with  dilute  sun  reds  are  listed  in  table  34,  ^mnp  2.  These  progenies 
consisted  of  four  color  types,  weak  purple,  weak  sun  red,  dilute  purple, 
and  dilute  sun  red,  in  the  numerical  relations  given  below: 

Color  types  ^^'^f 

''^  purple 

lb 

Observed 481 

Calculated 501 

Difference —20         +25         — 4i         +36  0 

The  deviations  from  equality  of  the  four  classes  expected  of  a  dihybrid 
are  so  great  that  they  would  not  occur  by  chance  alone  more  than  once 
in  twenty  trials,  P  equaling  0.05.  Dr.  Anderson's  notes  indicate  that 
there  was  considerable  difficulty,  in  the  case  of  two  of  the  cultures,  in  dis- 
tinguishing dilute  purple  from  dilute  sun  red.  Whether  this  difficulty 
may  account  in  part  for  the  poor  fit  is  not  known.  The  outstanding  fact, 
however,  is  the  appearance  of  the  four  classes  and  no  others.  Since 
weak  sun  red  is  known  to  differ  from  dilute  sun  red  by  the  factor  pai' 
B^'  b,  the  inference  is  clear  that  weak  purple  differs  from  dilute  purple  by 
Ihe  same  pair  and  by  no  others.  The  formvdae  assumed  for  the 
four  color  types  are,  therefore,  A  B^  PI,  A  B"'  pi,  A  b  PI,  and  A  b  pi, 
respectively. 

If  the  foregoing  conclusion  is  correct,  crosses  of  weak  sun  reds  with 
dilute  purples  should  give  weak  purples  in  Fi  and  the  same  four  color 
classes  in  F2  as  are  noted  above  for  crosses  of  weak  purple  with  dilute  sun 
red.  A  single  cross  of  a  dilute  purple  with  a  homozygous  weak  sun  red 
resulted  in  18  weak  purple  plants.  Two  crosses  of  dilute  purples  with 
weak  sun  reds  heterozygous  for  B^  b  gave  12  weak  purples  and  11  dilute 
purples.  That  the  production  of  weak  purples  in  these  crosses  was  not 
due  to  the  b  or  PI  factors  of  the  dilute  purple  parents  is  evidenced  by  the 
fact  that  crosses  of  the  same  dilute  purple  individuals  witli  sun  reds 
gave  full  purples  in  Fi.  One  of  the  Fi  weak  purples,  A  A  B'^  b  PI  pl, 
of  the  above  crosses  was  backcrossed  with  dilute  sun  red,  A  bpl,  with  the 
result  (table  34,  group  3)  showa  below.     The  expected  equality  of  the 


Weak 

Dilute 

Dilute 

sun  red 

purple 

sun  red 

iotai 

lib 

Ilia 

lYa 

28 

22 

27 

98 

24.5 

24.5 

24.5 

98 

72  R.  A.  Emerson 

four  color  types  was  closely  approached   in  the  results,  x^  equalmg  0.80. 
The  comparison  of  observed  with  expected  results  follows: 

!  Color  tj^es  "^^^^^ 

I  ''  ^  purple 

'  lb 

Observed 21 

Calculated 24 . 5 

Difference..- —3.5       +3.5       —2.5       +2.5  0 

The  progeny  of  a  purple  plant  heterozygous  for  B  B"^,  PI  pi,  and  the 
endosperm  color  pair  Y  ij,  backcrossed  with  a  white-seeded  weak  sun  red 
plant,  A  B^  pi  y,  affords  evidence  of  another  kind  with  respect  to  the 
interrelations  of  strong  and  weak  purple  and  of  strong  and  weak  sun  red. 
It  has  been  noted  previously  (page  60)  that  PI  pi  and  Yy  are  Imked,  with 
a  somewhat  irregular  percentage  of  crossing-over.  The  backcross  gave 
the  four  color  types  purple,  weak  purple,  sun  red,  and  weak  sun  red,  in 
the  numerical  relation  60:48:59:62.  The  observed  deviations  from  the 
equahty  expected  of  a  dihybrid  are  such  as  might  occur  by  chance  more 
than  once  in  two  trials,  P  equaling  0.54.  The  distribution  of  these  229 
plants  to  the  four  color  types  when  the  progeny  of  yellow  seeds  and  that 
of  white  seeds  are  considered  separately  is  as  follows: 


Color  types 

Purple 

vv  eaK 

purple 

Sun  red 

la 

lb 

Ila 

Yellow  seeds 

48 

36 
12 

8 

White  seeds 

12 

51 

Total 


Weak 

sun  red 

lib 

17  109 

45  120 


Evidently  weak  purple,  assumed  to  be  A  B""  Pi,  here  bears  the  same 
relation  to  weak  sun  red,  A  B"'  pi,  that  purple,  A  B  Pi,  ]&  known  to  bear 
to  sun  red,  A  B  pi.  In  case  of  the  purples  and  the  sun  reds  alone,  the 
linkage  of  PI  pi  with  Y  y  is,  shown  by  99  non-crossovers  to  20  crossovers, 
or  16.8  ±  2.7  per  cent  of  crossing-over.  When  the  weak  purples  and 
the  weak  sun  reds  are  alone  considered,  the  non-crossovers  are  to  the 
crossovers  as  81:29,  a  crossover  percentage  of  26.4  i  2.8.     While  the 


Weak 

sun  red 

lib 

Dilute 

purple 

Ilia 

Dilute 
sun  red 
IVa 

Total 

315 
125 

119 

280 

164 
317 

894 
830 

Plant  Colors  in  Maize  73 

difference  between  these  two  percentages  of  crossing-over,  9.G  ±  3.9,  is 
consiclera])le,  it  is  probably  not  statistically  significant,  P  equaling  0.09. 
Still  further  evidence  in  favor  of  the  assumption  that  weak  purple  is 
differentiated  from  dilute  purple  by  the  factor  pair  /i"'  b,  just  as  weak 
sun  red  is  differentiated  from  dilute  sun  red,  is  afforded  by  data  from  six 
of  the  progenies  recorded  in  group  2  of  table  34.  These  data,  it  will  be 
recalled,  were  obtained  from  Fi's  of  weak  purple  x  dilute  sun  rod  back- 
crossed  to  dilute  sun  red.  The  Fi  weak  purples  were  heterozygous  for 
liguleless  leaf  as  well  as  for  plant  color,  AAB^bPlplLglg,  and  the  dilute 
sun  reds  with  which  they  were  backcrossed  were  liguleless,  A  b  yl  Ig.  The 
1724  plants  were  distributed  as  follows: 

Color  types  ^\"^^^^ 

lb 

Normal  leaves 296 

Liguleless  leaves 108 

Evidently  the  linkage  relations  of  liguleless  with  weak  purple  and  dilute 
purple  are  similar  to  those  already  known  for  liguleless  with  weak  sun  red 
and  dilute  sun  red  (page  67).  Of  the  921  weak  svm  reds,  A  B^  pi,  and 
dilute  sun  reds,  A  b  pi,  632  belong  to  the  non-crossover  and  289  to  the 
crossover  class,  a  percentage  of  crossing-over  of  31.4  rb  1.0.  Similarly, 
of  the  803  weak  purples  and  dilute  purples,  the  non-crossovers  are  to 
the  crossovers  as  576:227,  a  percentage  of  crossing-over  of  28.3  ±  1.1. 
The  difference  between  these  two  percentages  of  crossing-over,  3.1  rb  1.5, 
is  such  as  might  occur  by  chance  once  in  six  trials,  P  equaling  0.16. 

By  way  of  summary,  it  may  be  noted  that,  from  appropriate  intercrosses 
of  the  several  color  typos  and  from  determinations  of  the  linkage  relations, 
of  these  types  with  liguleless  leaf  and  with  yellow  endosperm,  weak  purple 
and  weak  sun  red  have  been  shown  to  have  the  genotypes  A  W"  PI  and 
A  B^  pi,  respectively.  This  establishes  the  existence  of  the  triple  alle- 
lomorphs, B,  B'" ,  b.  There  is  some  evidence  in  favor  of  the  occurrence 
of  a  fourth  member  of  this  series,  b". 

CROSSES    INVOLVING    THE    MULTIPLE   ALLELOMORPHS    /?'',    Hf,   W^ ,    /,  1^ ,    r*^ 

In  an  earlier  section  of  this  account  (page  29)  dealing  with  crosses  involv- 
ing only  A  a,  B  b,  and  PI  pi,  three  types  of  green  plants  were  reported, 


74  R.  A.  Emerson 

namely,  a  B  pi  (Via),  ah  PI  (VIb),  abpl  (Vic).  Still  another  type  of 
green  —  a  type  wholly  devoid  of  purple,  red,  or  brown  pigment  —  has  been 
used  in  several  crosses,  with  results  quite  unlike  those  obtained  from  corre- 
sponding crosses  with  the  other  green  types.  For  reasons  that  })ecome 
apparent  later,  this  fourth  type  of  green  is  regarded  as  genetically  similar 
to  dilute  sun  red  and  is  known  as  type  IVg. 

Green  IVg  x  brown  V 

Generations  F\  and  F^. —  When  brown,  a  B  PI,  is  crossed  with  green 
of  any  of  the  three  types  previously  studied,  brown  appears  in  Fi  and 
brown  and  green  in  F2.  If  green  VTc,  a  b  pi,  is  used  in  the  cross,  the  F2 
ratio  approaches  9 : 7,  while  if  green  Via,  a  B  pi,  or  VIb,  a  b  PI,  is  used, 
3:1  F2  ratios  are  of  course  expected  (tables  19  and  20,  page  135).  In 
striking  contrast  with  such  results  are  those  obtained  from  a  cross  of 
brown  with  green  IVg.  Two  such  crosses  gave  78  purple  plants  in  Fi, 
and  a  third  cross  resulted  in  72  purple  and  63  sun  red  plants.  It  will  be ' 
recalled  that  just  such  results  as  these  were  obtained  from  crosses  of  dilute 
sun  red  with  brown  (tables  4  and  14,  pages  123  and  131).  The  brown  plant, 
2031-20,  which  gave  purple  and  sun  red  Fi  plants  when  crossed  with  green 
IVg,  was  the  identical  plant  previously  reported  (table  4,  group  2)  to  have 
given  55  purples  and  55  sun  reds  when  crossed  with  a  dilute  sun  red  plant. 
Moreover,  this  same  brown  plant  was  shown  (table  20,  group  2,  page  135) 
to  have  produced  from  self-pollination  82  browns  and  34  greens.  Evi- 
dently it  was  aa  B  B  PI  pl.  The  important  point  here  is  that  crosses 
of  brown  with  green  IVg  give  exactly  the  same  results  in  Fi  as  if  green 
IVg  were  a  dilute  sun  red,  A  A  bb  pl  pl. 

There  are  other  reasons,  in  addition  to  the  Fi  results  of  crosses  with 
brown,  for  supposing  that  green  IVg  has  the  factor  A.  When  the  pericarp- 
color  gene  P  occurs  together  with  A,  the  resulting  pericarp  color  is  always 
red,  but  when  P  and  a  a  are  associated  the  pericarp  color  is  brown.  When 
green  IVg  plants  have  pericarp  color  it  is  red  rather  than  brown,  while 
that  of  greens  Via,  VIb,  and  Vic  is  always  brown.  Again,  the  A  factor 
is  known  to  be  essential  to  the  production  of  aleurone  color  (Emerson, 
1918),  and  the  stock  of  IVg  green  plants  used  in  these  crosses,  a  strain 
of  the  variety  Black  Mexican  sweet  corn,  was  homozygous  for  purple 
aleurone.  It  is  noteworthy  in  this  connection  that  many,  perhaps  most, 
plants  of  this  variety  show  very  slight  traces  of  sun  red,  and  these  traces  are 


Plant  Colors  in  Maize  75 

limited  commonly  to  the  glumes  of  the  staminatc  inflorescence.  Appar- 
ently the  stock  of  green  IVg,  which  under  no  environmental  conditions 
to  which  it  has  been  subjected  has  ever  been  observed  to  produce  the 
slightest  trace  of  sun  red,  is  merely  an  extreme  minus  variation  of  dilute 
sun  red. 

Not  only  were  the  Fi  results  of  the  cross  of  brown  with  green  IVg  like 
those  of  the  cross  of  brown  with  dilute  sun  red,  but  the  same  major  color 
types  appeared  in  F2  (table  35,  page  145).  The  distribution  of  all  the  indi- 
viduals of  six  F2  progenies  to  the  six  major  color  types  heretofore  recognized 
is  compared  below  with  the  theoretical  distribution  calculated  on  the 
assumption  that  the  green  IVg  parent  was  genotj^pically  a  dilute  sun  red, 
A  Ahb  pi  pi: 

Color  types  Purple    Sun  red   ^jj.^*^  ^"^"^^^^  Brown  Green    Total 

Observed 309         100  67  19  88  98  681 

Calculated 287  96  96  32  96  74  681 

Difference +22        +4      —29      —13        —8       +24  0 

The  outstanding  features  of  this  comparison  are  the  relatively  small 
deviations,  in  comparison  with  the  number  of  individuals,  for  the  purple, 
sun  red,  and  brown  types,  and  the  relatively  large  deviations  for  the  dilute 
purple,  dilute  sun  red,  and  green  classes.  The  relative  importance  of 
the  several  deviations  is  best  seen  by  a  comparison  of  the  quotients  of 
calculated  frequencies  into  the  squares  of  corresponding  deviations,  from 
which  z2  and  P  are  derived  (Elderton's  and  Pearson's  tables).  These 
quotients  for  the  several  classes  are: 

T^       1  a  J  Dilute  Dihite  t>  n 

Purple         Sun  red  1  ■,  Brown  Green 

^  purple         sun  red 

1.69  0.17  8.76  5.28  0.67  7.78 

If  these  quotients  were  no  greater  in  the  case  of  dilute  purple,  dilute 
sun  red,  and  green  than  for  purple,  sun  red,  and  brown,  there  would  be 
about  two  chances  in  five  that  the  observed  deviations  might  be  due  merely 
to  errors  of  random  sampling,  a  fairly  good  fit  being  shown  —  /^  =  5.06, 
P  =  0.41.  But  as  they  stand,  these  deviations  could  be  expected  to  occur 
thru  chance  alone  not  more  than  once  in  five  thousand  similar  trials,  a 


76  'R.  A.  Emerson 

very  poor  fit  being  shown  —  z^  =  24.35,    P  =  0.0002.      Evidently,    green 
IVg  does  not  give  the  same  results  in  F2  of  this  cross  as  does  dilute  sun 

red. 

It  is  to  be  supposed,  of  course,  that  green  IVg  differs  in  some  essential 
genetic  way  from  dilute  sun  red,  else  it  would  not  remain  true  green  for 
generation  after  generation  while  the  typical  dilute  sun  red  constantly 
produces  a  conspicuous  amount  of  sun  red  pigment.  It  was  therefore  to 
be  expected  that  the  dilute  sun  red  class  would  be  deficient  in  F2  while 
the  green  class  would  show  a  corresponding  excess.  But  if  the  24  green 
plants  in  excess  of  the  calculated  number  be  added  to  the  dilute  sun  red 
class,  that  class  becomes  too  large  by  eleven  individuals,  the  excess  now 
becoming  almost  as  great  as  the  observed  deficiency.  Moreover,  the  dilute 
purple  class,  it  must  be  remembered,  remains  greatly  deficient.  If  it  be 
supposed  that  the  excess  of  greens  came  about  at  the  expense  of  dilute 
purples  as  well  as  of  dilute  sun  reds,  a  very  good  fit  of  observation  to  theory 
is  obtained'.  On  redistribution  of  the  24  greens  in  excess  of  expectation 
to  the  dilute  purples  and  dilute  sun  reds  in  the  3 : 1  relation  usually  existing 
between  these  classes,  the  corrected  distribution  for  the  six  classes  is  as 
shown  below.  There  are  almost  two  chances  in  five  that  the  deviations 
may  be  due  to  random  sampling,  P  equaling  0.38. 

Color  types      Purple  Sun  red  ^"^"^^^^  g^'^''^!^^^  Brown  Green    Total 

Corrected  distribu- 
tion       309        100  85  25  88  74  681 

Calculated 287  96  96  32  96  74  681 

Difference +22         +4      —11—7—8  0  0 

Mere  closeness  of  fit  cannot,  of  course,  be  regarded  as  proof  of  the 
supposition  on  which  the  corrected  distribution  was  made.  But  there  are 
other  considerations  which  greatly  strengthen  the  hypothesis.  In  the 
case  of  all  the  F2  progenies  listed  in  table  35,  it  was  o]:)served  that  some  of 
the  purple  plants,  altho  quite  as  strongly  colored  otherwise  as  normal 
purples,  had  wholly  green  anthers  in  place  of  the  usual  dark  purple  ones 
(Plate  I,  4).  Likewise  some  of  the  sun  red  plants  had  green  instead  of 
pink  anthers.  In  striking  contrast  to  this,  not  a  single  dilute  purple  or 
dilute  sun  red  plant  with  green  anthers  was  seen  hi  the  whole  lot,  the  dilute 


Plant  Colors  in  Maize  77 

purples,  so  far  as  observed,  having  dark  purple  anthers  and  the  dikite 
sun  reds  pink  anthers,  just  as  in  the  lots  considered  in  the  first  section  of 
this  paper.  Counts  of  the  purple  and  the  sun  red  plants  with  different 
anther  colors  were  made  for  only  three  of  the  six  F2  progenies  (table  36), 
and  for  these  lots  not  every  plant  was  noted  at  the  time  when  it  was  possible 
to  determine  the  anther  color  positively.  When  some  anthers  have  become 
dry  and  weathered,  it  is  impossible  to  tell  whether  they  were  pink  or  green 
when  fresh.  Less  difficulty  is  experienced  with  purple  anthers,  which 
hold  their  color  much  longer.  Unfortunately,  the  records  of  the  three 
F2  families  were  not  made  early  enough  for  positive  identification  of  anther 
color  of  all  plants.  Of  1G2  purple  plants,  117  had  purple  anthers  and  33 
had  green  anthers,  while  12  were  not  recorded.  Of  50  sun  red  plants,  21 
had  pink  anthers  and  12  had  green  anthers,  with  17  not  recorded.  In 
these  two  lots  the  plants  with  purple  and  pink  anthers  were  together 
about  three  times  as  numerous  as  those  with  green  anthers,  thus  suggest- 
ing a  simple  monohybrid  relation  between  colored  and  green  anthers. 

Working  hypothesis. —  If  the  genetic  factor  which  is  responsible  for  green 
anthers  of  purple  and  sun  red  plants  be  assumed  to  cause,  in  the  case  of 
dilute  purples  and  dilute  sun  reds,  not  merely  the  anthers  but  the  whole 
plant  —  leaves,  sheaths,  husks,  glumes,  stalk,  and  so  forth  —  to  be  green, 
a  satisfactoiy  working  hypothesis  is  afforded.  The  factor  concerned  here 
has  been  found  to  be  the  well-known  aleurone-color  factor  R,  or  else  some 
factor  very  closely  linked  with  it.  Some  of  the  evidence  on  which  this 
statement  is  based  is  presented  later  in  this  paper  (pages  80,  98).  It  may  be 
pointed  out  in  passing  that  the  relation  between  anther  color  and  aleurone 
color  here  noted  was  studied  by  Webber  (1906)  some  years  before  the 
several  aleurone-color  and  plant-color  factors  had  been  determined. 

Since  aleurone  color  is  not  primarily  concerned  in  the  present  account, 
it  might  be  less  confusing  if  the  case  were  regarded  as  one  of  complete 
hnkage,  and  if  some  other  symbol  for  anther  color  were  used  and  all 
reference  to  the  R  factor  omitted  in  this  paper.  Until  recently  there 
was  nothing  known  of  aleurone-color  })ehavior  that  made  necessary  the 
assumption  of  more  than  the  simple  factor  pair,  R  r.  The  plant-color 
behavior,  on  the  other  hand,  as  becomes  apparent  later,  necessitates  the 
assumption  of  a  group  of  multiple  allelomorphs  responsible  in  turn  for 
diverse  combinations  of  colors  of  leaves,  sheaths,  anthers,  silks,  and  other 
plant  parts.     The  commonest  combinations  in  the  writer's  cultures  are 


78  R.  A.  Emerson 

strong  pink  anthers  with  deep  red  silks,  hghter  pink  anthers  with  red- 
dish or  pinkish  silks,  green  anthers  with  green  silks,  and  so  on,  but  there 
exist  also  such  combinations  as  strong  pink  anthers  with  green  silks, 
green  anthers  with  reddish  silks,  and  the  like.  Moreover,  different  inten- 
sities of  dilute  sun  red  in  leaf  blades,  glumes,  and  other  parts  are  sometimes 
combined  with  various  silk-color  and  anther-color  combinations.  There 
is  evidence  that  at  least  several  of  these  combinations  behave  as  would  be 
expected  if  each  were  a  definite  unit  allelomorphic  to  any  one  of  the  others. 

Perhaps  the  most  remarkable  feature  of  this  series  of  allelomorphs  — 
or  supposed  allelomorphs  —  is  the  fact  that  a  single  unit  behaves  as  a 
dominant  with  respect  to  the  color  of  one  plant  part  and  as  a  recessive 
with  respect  to  that  of  another  part.  Thus,  a  combination  of  dominant 
pink  anthers  with  recessive  green  siUvS  is  common  in  the  writer's  cultures. 
The  wholly  green  plants  used  in  the  crosses  here  under  consideration  are 
recessive  for  green  silks,  anthers,  glumes,  sheaths,  husks,  and  other  parts, 
and  dominant  for  colored  aleurone.  Since  the  aleurone-color  symbols 
R  r  have  long  been  employed  in  the  usual  way,  R  as  the  dominant  and 
r  as  the  recessive  allelomorph,  this  usage  is  adhered  to  in  this  paper.  The 
effect  of  these  factors  on  plant  color  is  indicated  by  superscripts.  Thus, 
both  R^  and  /  are  dominant  allelomorphs  with  respect  to  pink  anthers 
and  reddish  silks,  while  both  R^  and  r^  are  recessive  for  green  anthers, 
silks,  and  so  on.  In  the  crosses  here  considered  it  is  known  that  /  and 
R^  are  the  pair  concerned.  With  respect  to  plant  color,  therefore,  as 
contrasted  with  aleurone  color,  /  is  dominant  and  R^  is  recessive.  While 
it  is  realized  that  this  usage  may  tend  to  confuse  the  hasty  reader,  the  use 
of  any  other  symbols  that  have  so  far  suggested  themselves  would  result 
in  greater  confusion  ultimately,  particularly  when  the  interrelations  of 
plant  color  and  aleurone  color  are  taken  up. 

To  return  to  the  F2  behavior  of  crosses  of  green  IVg  with  brown,  the 
following  notation  should  express  the  F2  results  obtained,  provided  the 
proposed  hypothesis   is  tenable: 


Phenotypes 

Plant  color 

Anther  col 

81- 

-ABPlr"-—      la 

Purple 

Purple 

27- 

-ABPIR"—     Ig 

Purple 

Green 

27- 

-AB'plr'-  —    Ila 

Sun  red 

Pink 

9- 

~ABplR"~   Ilg 

Sun  red 

Green 

27- 

-Ab  PI r'—  Ilia 

Dilute  purple 

Purple 

Plant  Colors  in  Maize  79 

Phenotypes  Plant  color  Anther  color 

Q—AhPlR"—  Illg  Green  Chven 

9  —  Ah  pi  r''   ■ —  /  Va  Dilute  sun  red  Pink 

S  —  AbpIR"  —I  Vg  Green  Green 

27  — a  B  PI  r'-—    V  Brown  Green 

Q  —  aBPIR"—    V  Brown  Green 

9  —  aBplr''   — Via  Green  Green 

3  —  aBplR"  —  Via  Green  Green 

9  —  abPlr'-    ^Vlb  Green  Green 

Z  —  abPlR"  —VIb  Green  Green 

3  —  abj)l  r''     —  Vic  Green  Green 

1  —  abplR"  —  Vic  Green  Green 

256 

The  theoretical  numerical  relation  between  the  several  color  combi- 
nations, in  the  order  given  above  except  that  all  greens  are  included  in  the 
last  class,  is  81:27:27:9:27:9:36:40,  total  256. 

The  distribution  of  the  353  individuals  of  the  three  F2  progenies  for 
which  anther  records  were  made  (table  36,  page  146)  is  compared  below 
with  the  theoretical  distribution.  In  order  that  all  plants  may  be  included, 
the  few  purple  and  sun  red  plants  whose  anther  colors  were  not  noted 
are  arl^itrarily  distributed  to  the  colored-anther  and  green-anther  classes 
in  a  3 : 1  ratio.  The  fit  of  observation  to  hypothesis  is  so  good  that  there 
are  three  chances  in  five  that  the  deviations  may  be  due  to  errors  of  random 
sampling,  P  equaling  0.60. 

Plant  color        Purple  Purple  Sun  red  Sun  red  ^^[."^^j^  ^^^^^^  Brown       Green  Total 

Anther  color      Purple  Green  Pink  Green  Purple  Pink  Green  Green 

la           Ig  Ila  Ilg        Ilia  Wa  V  Illg,  IVg,  VI 

Observed 126          36  M  16          39  10  42  50  353 

Calculated 112         37  37  12          37  12  50  55  352 

Difference -\-U       —1         —3         +4         -^2        —2        —8  —5  -|-1 

TMien  the  six  Fo  progenies  listed  in  table  35,  for  three  of  which  no  records 
of  anther  color  were  made,  are  grouped  without  reference  to  anther  color, 
the  comparison  of  observed  and  calculated  numbers  are  as  given  below. 
For  the  six  progenies  there  is  practically  an  even  chance  that  the  devia- 
tions ma}^  be  due  to  errors  of  random  sampling,  P  equaling  0.48.  It  will 
be  recalled  that  when  these  same  progenies  were  compared  with  the  dis- 


Purple 

Sun  red 

Dilute 
purple 

Dilute 
sun  red 

BrowTi 

Green 

Total 

la 

Ila 

Ilia 

IVa 

V 

Illg,  IVg,  VI 

309 

100 

67 

19 

88 

98 

681 

287 

96 

72 

24 

96 

106 

681 

80  R.  A.  Emerson 

tribution  calculated  on  the  basis  of  the  three-factor  hypothesis,  the  fit 
was  very  poor,  P  equaling  0.0002  (page  76).  Comparison  of  the  observed 
distribution  with  the  distribution  calculated  on  the  four-factor  basis  follows : 

Color  types 

Observed 

Calculated 

Difference -^22         +4  —5  —5  —8  —8  0 

Relation  of  aleurone  color  to  plant  color. —  It  is  evident  from  the  compari- 
sons already  given  that  the  four-factor  hypothesis  fits  well  the  F2  data, 
which  is  of  course  to  be  expected  since  it  was  invented  for  that  purpose. 
But  this  fact  alone  is  far  from  a  substantiation  of  the  hypothesis.  The 
genetic  tests  ordinarily  available  are  the  behavior  of  the  several  F2  types 
in  later  generations  and  in  intercrosses.  Since  aleurone  color  as  well  as 
plant  color  is  involved  in  these  crosses,  still  another  test  can  be  employed. 
The  six  Fi  plants  whose  Fo -progenies  are  recorded  in  table  35  produced 
from  self-pollination  a  total  of  955  seeds,  of  which  388  had  colored  and  567 
colorless  aleurone.  This  obviously  approaches  closely  a  27:37  ratio,  the 
percentage  of  colorless  seeds  being  59.4  ±1.1  while  the  theoretical  per- 
centage is  57.8  (Emerson,  1918).  The  deviation  from  expectation, 
1.6  ±  1.1  per  cent,  is  such  as  might  be  expected  by  chance  once  in  three 
trials,  P  equaling  0.33.  Evidently,  therefore,  the  aleurone  factors  A,  C, 
and  R  are  concerned  in  these  crosses.  Since  A  and  R  are  assumed  by  the 
hypothesis  to  be  plant-color  factors  also,  there  is  afforded  opportunity  of 
comparing  the  plant-color  classes  fi'om  colored  with  those  from  color- 
less seeds.  Since  colored  aleurone  requires  the  interaction  oi  A,  C,  and  R, 
colored  seeds  should  never  produce  brown  j^lants  nor  green  plants  of  type 
VI,  both  of  which  are  a  a.  As  seen  from  the  data  given  below,  no  brown 
plants  came  from  colored  seeds  but  a  few  wholly  green  plants  appeared. 
Greens  of  type  IVg  are  of  course  to  be  expected  from  seeds  homozygous 
for  R^.  Owing  to  the  fact  that  a  larger  percentage  of  colorless  than  of 
colored  seeds  produced  plants,  the  theoretical  distribution  with  respect 
to  plant  color,  given  below,  was  calculated  separately  for  colored  and  for 
colorless  seeds.     J^or  the  colored  seeds  there  are  nearly  two  chances  in 


Plant  Colors  in  Maizk  81 

five  (P  equaling  0.58),  and  for  the  colorless  seeds  only  about  one  chance  in 
fovn-teen  (P  equaling  0.07),  that  the  observed  deviations  may  be  due  to 
errors  of  random  sampling.     The  comparisons  follow: 

Color  types  Purple     Sun  red     ^^'[.'J^J*^    ^^''^^^^       Brown         Green  Total 

la  Ila  Ilia  R'a  V  Illg,  IVg,  VI 
Colored  seeds: 

Observed 14S  .51  25              8  0  23  255 

Calculated 143  48  32  11  0  21                   255 

Difference +5  +3  —7  —3  0  +2  0 

Colorless  seeds: 

Observed 161  49  42  11  88  75  420 

Calculated 136  45  39  13  104  89  426 

Difference +25  +4  +3  —2  —16  —14  0 

It  is  noteworth}^  that  the  ratio  of  purples  and  sun  reds  to  dilute  purples 
and  dilute  sun  reds  is  considerably  greater  for  plants  grown  from  colored 
seeds  than  for  those  from  colorless  seeds.  This  is  to  be  expected  from 
the  fact  that  R  must  be  present  in  all  colored  seeds,  while  some  of  the 
colorless  seeds  here  concerned  were  doubtless  r  r.  Hence,  R^  R^  should 
have  occurred  more  frequently  in  the  colored  than  in  the  colorless  seeds, 
and  should,  by  the  hypothesis  here  under  test,  have  reduced  the  numbers 
of  dilute  purples  and  dilute  sun  reds,  causing  these  plants  to  appear  as 
greens,  types  Illg  and  IVg.  If  the  23  green  plants  grown  from  colored 
seeds  are  added  to  the  dilute  purples  and  dilute  sun  reds,  the  ratio  of 
strong  to  dilute  purples  and  sun  reds  approaches  closely  the  ratio  observed 
for  the  plants  from  colorless  seeds. 

It  is  even  more  instructive  to  note  the  relation  of  aleurone  color  to  plant 
color  in  the  case  of  the  three  F2  lots  for  which  anther  colors  were  recorded 
(table  36,  page  146).  For  this  comparison  the  few  purple  and  sun  red 
plants  whose  anther  colors  were  not  recorded  have  been  distributed  to 
the  colored-anther  and  green-anther  classes  in  approximately  the  ratio 
in  which  these  anther  colors  were  found  to  occur  in  the  cases  in  which  anther 
colors  were  recorded.  Since  a  larger  proportion  of  colorless  than  of  colored 
seeds  produced  plants,  the  theoretical  (list rilnit ion  has  i)cen  calculated 
separately  for  the  two  classes  of  seeds.     The  comparisons  follow: 


82  *  R.  A.  Emerson 

Plant  color        Purple  Purple  Sun  red  Sun  red  ^pjg  guli  red  ^^^"^      ^'"^^^           ^^^^^ 

Anther  color      Purple  Green     Pink      Green    Purple  Pink    Green       Green 

la  Ig         Ila          Ilg        Ilia  IVa         V    Illg,  IVg,  VI 
Colored  aleurone: 

Observed 48  25           11           12           16  4            0            10                126 

Calculated 47  24          16           8          16  5           0            10                126 

Difference +1         +1—5+4  0—10  0  0 

Colorless  aleurone: 

Observed 78  11  23  4  23  6  42  40  227 

Calculated 62  10  21  4  21  7  55  47  227 

Difference +16        +1        +2  0        +2        —1      —13  —7  0 

In  view  of  the  rather  large  number  of  plant-color  classes  and  the  com- 
paratively small  number  of  individuals  concerned  here,  the  fit  of  the 
observed  to  the  theoretical  distribution  is  remarkably  good.  The  devia- 
tions are  such  as  might  be  expected  by  chance  seven  times  in  ten  trials 
for  the  colored-seeded  lot  (P  =  0.70),  and  about  once  in  four  trials  for  the 
colorless-seeded  lot  (P  =  0.26).  In  addition  to  this  comparison  of  the 
lot  as  a  whole,  it  should  be  noted  that,  while  among  the  purple  and  sun  red 
plants  as  a  whole  the  expected  relation  of  colored  (purple  and  pink) 
anthers  to  colorless  (green)  anthers  i.s  3:1,  for  the  colored-seeded  lot  it 
is  2:1  and  for  the  colorless-seeded  lot  it  is  6:1.  The  observed  relations 
were  59:37  and  101:15,  or  about  1.6:1  and  6.7:1,  respectively.  On  the 
whole,  therefore,  this  comparison,  involving  aleurone  color  as  well  as  plant 
color,  supports  the  suggested  factorial  interpretation. 

Later  behavior  of  F2  purple  I. —  Only  three  F2  purples  with  purple  anthers 
were  tested  in  F3.  One  of  these,  2960-9,  resulted  in  purple  plants  with 
purple,  la,  and  green,  Ig,  anthers,  and  sun  red  plants  with  pink,  Ila,  and 
green,  Ilg,  anthers,  in  the  respective  numbers  14:9:6:3.  A  purple  plant 
of  the  genotype  A  A  B  B  PlplB!'  /  should  give  these  four  classes  in 
the  relation  18:6:6:2,  The  observed  deviations  might  be  expected  twice 
in  five  trials,  P  equaling  0.41. 

Another  F2  purple  plant,  2958-8,  gave  F3  progeny  consisting  of  the  same 
eight  color  types  as  were  seen  in  F2  in  table  36  (page  146) .  Evidently  the 
F2  purple  plant  w^as  A  a  B  bPlpl  R^  /.  The  deviations  from  expecta- 
tion are  such  as  might  occur  by  chance  in  about  seventeen  out  of  any 
twenty  such  trials,  P  equaling  0.86.     The  comparison  follows: 


Plant  Colors  in  Maize  83 


Plant  color         Purple  Purple  Sun  red  Sun  red 

Anther  color       Purple   Green  Pink     Green 

la           Ig  Ila        Ilg 

Observed 28           13  11             3 

Calculated 29          10  10            3 


Dilute 
purple 

sun  red  ^^°^'^      ^reen       Total 

Purple 

Pink     Green       Green 

Ilia 

IVa          V     IIIr,  IVg  ,VI 

7 

3           IG             11                 02 

10 

3           13             14                02 

Difference —1         +3        +1  0—3  0         +3  —3  0 

The  third  purple-ant hered  Fo  purple  tested,  29G1-3,  gave  in  Fs  all  the 
color  types  except  dilute  purple.  Ilia,  and  dilute  sun  red,  IVa.  A  purple 
plant  of  the  genotype  AaBBPlplR^f  should  give  the  color  types 
observed.  The  observed  deviations  from  expectation  might  occur  by 
chance  about  once  in  seven  trials,  P  equaling  0.15.  The  comparison 
follows: 

Plant  color            Purple  Purple  Sun  red  Sun  red  Brown  Green  Total 

Anther  color          Purple  Green     Pink      Green     Green  Green 

la           Ig          Ila         Ilg           V  VI 

Observed 37          11            5            2          12  3  70 

Calculated 30          10          10            3          10  8  71 


Difference +7         +1        —5        —1         +2        —5  — 1 

A  single  green-anthered  F2  purple,  2960-7,  gave  four  F3  color  types, 
purple,  sun  red,  brown,  and  green,  all  with  green  anthers.  This  behavior 
is  to  be  expected  from  an  F2  genotype  A  a  B  B  PI  pi  R^  R^.  One  of  the 
F3  purples,  4956-1,  repeated  this  l)ehavior  in  F.i.  The  F3  and  F4  progenies 
are  shown  together  in  the  following  comparison,  for  which  P  =  0.60: 

Color  types  Purple 

Ig 

Observed 84 

Calculated 86 

Difference —2  —2  +6  —2  0 

It  is  of  interest  to  note  in  this  connection  that  a  plant  of  the  genotype 
AaBB  PlplR'^  R^  could  not  exhibit  a  27:37  fatio  of  colored  to  color- 
less aleurone,  as  was  the  case  for  some  of  the  plants  dealt  with  earlier. 


Sun  red   Brown 

Green 

Total 

Ilg            V     . 

VI 

27            35 

7. 

153 

29            29 

9 

153 

84  R.  A.  Emerson 

For  A  a  fl"  R"  the  aleurone-color  ratio  must  be  either  9 : 7  or  3 : 1,  depending 
on  whether  the  third  aleurone-factor  pair  is  C  c  or  C  C.  The  F2  purple 
plant  2960-7  showed  a  9:7  aleurone-color  ratio  with  86  colored  and  74 
colorless  seeds,  AaCcRR,  while  the  F3  plant  4956-1  exhibited  a  3:1 
ratio  with  213  colored  and  67  colorless  seeds,  A  aC  C  R  R.  Another 
purple  plant  of  the  same  F3  progeny,  4956-32,  exhibited  a  3 : 1  aleurone- 
color  ratio  and  threw  only  green-anthered  purple  and  sun  red  plants.  Its 
genotype  must  have  been  A  A  B  B  C  c  Plpl  R"  R^.  Thus  it  is  often 
possible,  from  behavior  in  the  following  generation,  to  know  the  genotype 
not  only  with  respect  to  plant  color  but  for  aleurone  color  as  well.  This 
is  particularly  true  when  the  B  factor  is  present. 

Of  the  twenty-four  sorts  of  behavior  possible,  according  to  hypothesis, 
for  F2  purples  of  the  cross  under  consideration,  four  sorts  have  been 
exhibited  in  F3  and  a  fifth  shown  in  F4.  This  is  far  from  an  adequate 
study  of  the  F2  purples.  All  that  can  be  claimed,  therefore,  is  that,  so 
far  as  they  go,  the  results  are  in  accord  with  the  hypothesis. 

Behavior  of  other  F2  color  types. —  Only  oie  F2  sun  red  plant  with  pink 
anthers,  2961^,  was  tested  in  F3.  It  produced  sun  reds  with  pink  and 
sun  reds  with  green  anthers,  dilute  sun  reds,  and  greens.  Since  anther 
color  was  noted  for  only  a  part  of  the  plants,  it  has  to  be  disregarded  in 
classifying  the  F3  progeny.  The  color  types  sun  red,  dilute  sun  red, 
and  green  occurred  in  the  numerical  relation  114:23:57.  Of  the  eight 
possible  genotypes  of  pink-anthered  sun  red,  only  three  could  throw 
these  three  color  classes  —  Aa  B  h/  /,  A  A  B  h  R^  /,  and  Aa  B  h  R"  /. 
From  the  first  genotype  a  9:3:4,  from  the  second  a  12:3:1,  and  from  the 
third  a  36 : 9 :  19,  relation  should  exist  between  the  F3  classes.  The  poor 
fit  of  observed  numbers  to  the  9:3:4  relation  makes  it  improbable  that 
the  first  genotype  is  concerned,  there  being  only  about  one  chance  in 
twenty-two  that  the  ol^served  deviations  are  due  to  errors  of  random 
sampling,  P  equaling  0.045.     The  comparison  follows: 


Color  types 

Sun  red 
Ila 

Observed.  . 

114 

Calculated . 

109 

Difference. 

+5 

Green     Total 


Dilute 

sun  red 

IVa  Via,  c 

23  57            194 

36  49            194 

—13  +8                0 


Plant  Colors  in  Maize  85 

A  moro  conclusive  reason  for  throwing  out  the  first  genotype  is  the 
fact  that  the  phmt  had  some  seeds  with  colored  aleurone,  which  would 
have  been  impossil)le  if  it  were  i-  r.  The  second  genotype  is  discarded 
because  of  the  extremely  poor  fit  of  observed  numl)ers  to  the  12:3:1 
relation.  There  is  an  almost  inconceivably  small  chance  that  thc^  observed 
deviations  may  be  due  to  errors  of  random  sampling,  x-  (equaling  ISO. 
(When  n'  =  3  and  x~  =  29,  P  =  0.000001.  Higher  values  of  /'  when  iV  -  3 
are  not  listed  in  Pearson's  tables.)     The  comparis:)n  follows: 

Color  types  Sun  red   ^'^^^*^     Green       Total 

sun  red 

Ila,  g       IVa  IVg 

Observed 114  23  57  194 

Calculated 146  36  12  194 


Difference —32        —13         +45  0 

The  elimination  of  the  first  two  genotypes  leaves  the  third  genotype 
as  the  only  one  that  can  be  concerned  here.  The  fit  of  observed  numbere 
to  the  36 : 9 :  19  relation  is  very  close,  x^  equaling  0.84.  (Values  of  P  are 
not  listed  in  Pearson's  tables  for  values  of  x-  less  than  1;  when  x^  =  1 
and  n' =  3,  P  =  0.6].)     The  comparison  follows: 

Color  types  Sun  red   J^}}""}^^ 

Ha,  g 

Observed 114 

Calculated 109 

Difference +5  — 4  — 1  0 

This  comparison  leaves  little  doubt  that  the  genotype  of  the  F2  plant 
concerned  is  AaBbR^/.  There  are,  moreover,  other  considerations 
which  go  far  toward  identifying  the  genotype  as  given  here.  The  fact 
that  some  sun  red  plants  of  F3  had  green  and  others  pink  anthere  is  evidence 
for  the  constitution  R'  /.  Since  dilute  sun  red  plants  appeared  in  F3, 
there  can  be  no  question  as  to  B  h.  The  F2  plant  showed  a  9:7  aleurone- 
color  segregation,  and  therefore,  in  addition  to  R  r,  it  must  have  been 


rired      ^^^^" 

Total 

:Va    IVg,  Via,  c 

23              57 

194 

27              58 

194 

g6  R.  A.  Emerson 

either  A  a  or  C  c.  An  F3  sun  red  plant  with  green  anthers,  R"  R",  had 
97  colored  and  20  colorless  seeds,  again  indicating  either  A  a  or  C  c.  If  it 
was  A  A  B  b  C  c  R^  R'^,  both  colored  and  colorless  seeds  should  have 
given  sun  red  and  green  plants  in  a  3:1  ratio;  if  it  was  A  a  B  B  C  C  R" R^, 
the  colored  seeds  should  have  given  sun  red  and  the  colorless  ones  green 
plants  only,  the  plant-color  ratio  again  being  3:1;  but  if  it  was  A  aBh 
C  C  R^  R^,  the  colored  seeds  should  have  produced  sun  red  and  green 
plants  in  a  3 : 1  ratio  and  the  colorless  seeds  green  plants  only,  the  ratio 
of  sun  reds  to  greens  in  the  two  lots  together  being  9:7.  Actually  the 
colored  seeds  resulted  in  23  sun  red  and  10  green  plants  and  the  colorless 
seeds  in  10  green  plants  only,  the  ratio  of  sun  reds  to  greens  being  23 :  20, 
thus  approaching  9:7.  There  is,  therefore,  considerable  assurance  that 
the  F3  plant  was  AaBhC  C  R^  i^^-  that  the  Fa  plant  was  AaBhC  C 
R^  /,  and  that  the  F3  numerical  relation  of  plant  colors  was  36:9:19,  as 
originally  suggested  by  the  closeness-of-fit  test. 

A  single  dilute  purple  plant  of  F2,  2960-4,  was  tested  in  F3  and  found 
to  give  38  dilute  purple  and  39  green  plants.  Of  the  eight  possible  geno- 
types for  F2  dilute  purples,  the  only  ones  that  could  give  only  dilute 
purples  and  greens  in  F3  are  A  A  h  h  PI  PI  R^  /,  A  a  h  h  PI  PI  /  /,  and 
Aahh  PIPIR^ /.  The  first  two  should  give  a  3:1,  and  the  third  a 
9:7,  F3  ratio.  The  plant  had  colored  aleurone,  which  throws  out  of 
consideration  the  second  genotype  with  r  r.  The  F3  plant-color  ratio  fits 
fairly  well  a  9 : 7  but  not  at  all  a  3 : 1  expectation,  the  observed  numbers 
being  38 :  39  and  the  calculated  numbers  43 :  34  and  58 :  19,  with  deviations 
of  5  and  20,  and  probable  errors  of  2.6  and  2.9,  respectively.  The  deviation 
from  a  9:7  ratio  might  occur  by  chance  once  in  five  trials,  P  equaling  0.20, 
but  that  from  a  3 : 1  ratio  not  more  than  twice  in  about  a  million  trials, 
P  equaling  0.000002.  The  genotype  AahhPlPlR"/  is  therefore 
decidedly  favored  by  these  results.  The  aleurone-color  record  shows  that 
this  genotype  is  possible,  since  there  were  57  colored  and  56  colorless 
seeds,  a  relation  about  halfway  between  the  9:7  and  the  27:37  ratio 
due  io  A  aC  C  Rr  and  A  a  C  c  Rr,  respectively. 

Intercrosses  of  Fi  color  types 

It  is  realized  that  the  tests  of  Fo  types  by  studies  of  their  behavior  in 
later  generations  as  reported  above,  are  markedly  inadequate  to  serve 


Plant  Colors  in  Maize  87 

as  a  demonstration  of  the  hypothesis  suggested  to  account  for  the  F2 
behavior  of  the  cross  of  brown,  type  V,  with  green,  type  IVg.  It  is  note- 
worthy, however,  that  no  resuUs  have  been  found  that  do  not  agree  with 
the  hypothesis.  Fortunately,  several  intercrosses  of  the  types  found  in 
F2  afford  additional  evidence. 

Purple  Ig  x  green  Vic. —  Green-anthered  purples,  A  B  PI  RF,  crossed 
with  greens  of  type  Vic,  a  h  pi  f,  should  give  F2  results  identical  with 
those  found  from  the  original  cross  of  brown,  a  B  PI  f,  with  green  of 
type  IVg,  A  b  pi  R'',  since  Fi  in  either  case  should  be  A  a  B  bPl  pi  R^  /. 
Two  such  crosses  are  recorded  in  table  37,  group  1  (page  146).  The  Fi 
plants  were  both  purple,  with  purple  anthers.  In  F2  the  same  eight 
t,ypes  were  noted  as  in  Fo  of  the  cross  of  brown  with  green  IVg  (table  36). 
The  anther  color  was  not  recorded,  however,  for  many  of  the  plants, 
so  that  only  six  color  classes  are  shown,  as  in  table  35.  While  all  the 
expected  color  types  are  present,  the  fit  of  observed  to  calculated  numbers 
is  so  poor  that  the  observed  deviations  should  not  occur  by  chance  more 
than  once  in  thirty  trials,  P  equaling  0.033.     The  comparison  follows: 

Color  types  Purple  Sun  red     ^  ^,^         ^^    ,  Brown        Green  Total 

-'  ^  ^  purple   sun  red 

la.  g      Ila,  g      Illa       IVa  V      Illg,  IVg,  VI 

Observed....       80  13  9  9  20  27  158 

Calculated...       66  22  17  6  22  25  158 


Difference...    +14        —9        —8         +3        —2  f2  0 

If,  notwithstanding  the  poor  fit  shown  above,  the  Fi  was  A  a  B  b  PI 
pi  R"  /,  a  backcross  of  Fi  with  green  of  type  Vic,  a  b  pi  /,  should  result 
in  the  same  six  major  plant-color  types,  but  no  green-anthered  purples 
or  sun  reds  should  occur.  Such  crosses  are  listed  in  group  2  of  table  37. 
All  the  purple  plants  had  purple  anthers  and  all  the  sun  red  plants 
had  pink  anthers.  Moreover,  the  six  color  classes  appeared  in  so  very 
nearly  the  expected  relation  of  1:1:1:1:1:3  that  deviations  as  great  as 
those  observed  might  be  expected  to  occur  by  chance  perhaps  ninety-nine 
times  in  one  hundred  trials,  x^  equaling  0.85  (when  x^  ~  1  and  n'-  6, 
P  =  0.96).     The  comparison  follows: 


88  11.  A.  Emerson 

Color  types       Purple  Sun  red  ^^^^^  g^^^  'Jg^  Brown    Green      Total 

la  Ila        Ilia        IVa-        V  VI 

Observed 36  29  31  31  31  95  253 

Calculated 31.0       31.6       31.6       31.6       31.6       94.9       252.9 

Difference +4.4    —2.6    —0.6    —0.6    —0.6     +0.1       +0.1 

If  an  Fi  supposedly  A  a  B  bPlpl  R^  r-^,  be  backcrossed  to  dilute 
sun  red,  type  IVa,  Ab  pi  /,  color  types  la,  Ila,  Ilia,  and  IVa  should 
appear,  none  of  them  with  green  anthers.  Such  crosses  are  presented  in 
group  3  of  table  37.  The  anthers  thruout  were  purple  or  pink,  and  the 
several  color  types  appeared  in  approximately  equal  numbers,  as  expected, 
there  being  more  than  two  chances  in  five  that  the  observed  deviations 
may  have  been  due  to  errors  of  random  sampling,  P  equaling  0.42.  The 
comparison  follows: 

Color  types  Purple    Sun  red     ^'^^^^f^     ^^'^^""^^^        Total 

la  Ila         Ilia  IVa 

Observed 115  97  95  111  418 

Calculated 104.5       104.5       104.5       104.5  418 

Difference +10.5      —7.5      —9.5       +6.5'  0 

If  the  same  Fi  genotype,  A  a  B  h  PI  pi  R"  /,  he  backcrossed  with 
green  of  type  IVg,  A  bplR",  there  should  occur  five  major  color  types, 
brown  not  appearing,  and  both  green  and  colored  anthers  should  be 
found  in  ])oth  the  purple  and  the  sun  red  plants.  The  records  of  such 
a  cross  are  given  in  group  4  of  table  37.  The  seven  expected  color  types 
occurred  in  numljers  near  enough  to  expectation  so  that  there  are  nearly  three 
chances  in  ten  that  the  deviations  may  have  been  due  to  errors  of  random 
sampling,  P  equaling  0.29.  The  most  pronounced  deviations  are  the  excess 
of  dilute  sun  reds  and  the  deficiency  of  greens.     The  comparison  follows: 

Plant  color                      Purple  Purple  Sun  red  Sun  red   ^''"!®  Dilute    ^^^^     ,j,^^„j 

^             ^  purple  sun  red 

Anther  color                    Purple    Green  Pink      Green    Purple  Pink      Green 

la          Ig  Ila           Ilg        Ilia  IVa    Illg,  IVg 

Observed 10           i:j  7            S           10  15               1.3             76 

Calculated .• 9.5         9.5  9  5        9.5         9.5  9.5           19             76 

Difference +0.5    +3.5      -2.5    —1.5     +0.5     +5.5        —6  0 


Plant  (  ulous  in  Maize  89 

In  conclusion  it  seems  safe  to  say  that  the  cross  of  gi'een-anthered 
purpl(\  Ig,  with  green  of  type  Vic,  havS  given  results  similar  to  those 
yielded  by  the  cross  of  brown.  V,  with  green  of  type  IVg.  Since  this 
was  to  have  been  expected  from  the  hypothesis  suggested  by  the  F2 
generation  of  the  latter  cross,  the  results  just  discussed  lend  support  to 
that  hypothesis. 

Purple  Ig  x  dilute  sun  red  IVa. —  In  accordance  with  the  hypothesis 
under  consideration,  green-anthered  purple  is  A  B  PI  R^  and  dilute  sun 
red  is  A  h  pi  /.  Fi  of  the  cross  should  he  A  A  B  b  PI  pi  P!'  /,  and  F2 
should  consist  of  the  five  major  color  types,  purple,  sun  red,  dilute  purple, 
dilute  sun  red,  and  green  of  types  Illg  and  IVg,  with  both  green-anthered 
and  colored-anthered  subclasses  of  purples  and  sun  reds.  The  Fi  plants 
were  purple-ant hered  purples,  as  expected.  Three  F2  progenies  are 
recorded  in  table  3$,  group  1.  Anther  color  could  not  be  recorded  in 
all  cases,  but  in  each  of  the  three  F2  progenies  both  green  and  colored 
anthers  were  noted  for  both  purple  and  sun  red  plants.  In  one  progeny, 
5042-5045,  of  a  total  of  57  purples  and  sun  reds,  41  had  colored  and  16 
had  green  anthers,  which  is  not  far  from  the  expected  3 : 1  relation.  The 
415  F2  plants  w^re  so  distributed  among  the  five  color  classes  that  the 
chances  are  nearly  three  in  five  that  the  deviations  observed  may  have 
been  due  to  errors  of  random  sampling,  P  equaling  0.58.  A  comparison  of 
observed  and  theoretical  distributions  follows: 

Color  tvpes  Purple  Sun  red  1  ,    Green     Total 

^  ^  ^  purple  sun  red 

la,  g      Ila,  g       Ilia       IVa     IHg,  IVg 

Observed ,       243  71  59  22  20  415 

Calculated 234  78  58  19  26  415 

Difference +9        —7         +1         +3  —6  0 

An  Fi  of  the  cross  here  considered,  6557-12,  A  A  Bh  Pi  pi  R"  /,  was 
backcrossed  to  a  dilute  sun  red,  A  b  pi  /.  Four  color  types  occurred  in 
the  progeny,  as  expected,  and  all  the  plants  had  colored  anthers.  The 
deviations  from  expectation  were  such  as  might  occur  by  chance  in  consider- 
ably more  than  one  out  of  any  two  such  trials,  P  equaling  0.56.  The 
comparison  follows: 


R.  A.  Emerson 

Purple    Sun  red 

Dilute 
purple 

Dilute 
sun  red 

Total 

la           Ila 

Ilia 

IVa 

43            43 

35 

48 

169 

42            42 

42 

42 

168 

90 

Color  types 

Observed " 

Calculated 

Difference +1  +1  —7  +6  +1 

Purple  la  x  green  IV g. —  The  cross  between  purple  la  and  green  IVg 
should  have  given  results  identical  with  those  expected  from  the  cross 
of  green-anthered  purple  with  dilute  sun  red.  Tho  parents  are  supposed 
to  have  been  A  BPl/  and  A  b  pi  R\  and  the  Fi,  therefore,  A  A  B  h  PI 
pi  R^  /.  The  Fi's  were  purple-anthered  purples.  Two  r2  progenies  are 
listed  in  table  38,  group  2.  All  the  expected  color -types  occurred,  but 
the  observed  frequency  distribution  was  such  as  might  be  expected  to 
occur  by  chance  only  about  once  in  eleven  trials,  P  equaling  0.09.  If 
these  progenies  are  grouped  into  five  classes,  anther  color  being  disregarded, 
the  fit  is  somewhat  better,  P  equaling  0.16.  The  comparison  of  observed 
and  theoretical  frequencies  follows: 

Plant   color  Purple  Purple    Sun  red  Sun  red  ^^^^^f    ''^'^"H  Green       Total 

^  ^  purple   sun  red 

Anther  color                      Purple  Green  Pink  Green  Purple  Pink     Green 

la          Ig  Ila  Ilg  Ilia  IVa  Illg,  IVg 

Observed 26          14  17  3  9  2            1              72 

Calculated: 31          10  10  3  10  3            5              72 

Difference —5         +4  +7  0  —  1        —1        —4  0 

The  F2  of  this  cross  exhibited,  as  expected,  practically  the  same  results 
as  were  obtained  from  the  cross  of  green-anthered  purple  with  dilute 
sun  red.  Unlike  that  cross,  the  one  under  consideration  here  was  checked 
by  the  behavior  of  some  of  its  F2  types  in  later  generations. 

A  single  F2  purple-anthered  purple  produced  in  F3  16  plants  (table  39, 
group  1),  including  only  purple,  sun  red,  and  dilute  purple  in  the  relation 
9:4:3.  Of  both  the  purples  and  the  sun  reds,  some  plants  had  colored 
and  some  had  green  anthers.  Obviously  two  other  types,  dilute  sun  red  and 
green,  should  occur  in  such  an  F3  and  doubtless  would  have  been  found 
had  a  larger  number  of  plants  been  grown,  for  the  F2  plant,  in  order  to  have 
produced  the  color  types  recorded,  must  have  been  A  A  B  b  Plpl  R'  /. 


Plant  Colors  in  Maize  91 

Only  one  plant  of  each  of  the  missing  classes  was  to  have  been  expected, 
and  the  distribution  as  a  whole  was  not  far  from  expectation,  P  equaling 
0.59.  Both  the  types  lacking  in  F3  occurred  in  F4,  a  pink-anthered  sun 
red  F:i  producing  sun  reds  and  dilute  sun  reds,  while  green-anthered 
purples  produced  in  one  instance  purples,  sun  reds,  and  greens,  and  in 
another  instance  purples  and  greens  only,  all  with  green  anthers.  This 
F3  lot  may  consequently  l)e  regarded  as  A  A  B  b  PI  pi  R"  /,  and  therefore 
equivalent  to  the  F2  lot  from  which  it  came,  and  its  F4  progenies  equivalent 
to  F3  progenies. 

A  second  F2  purple-anthered  purple  was  backcrossed  to  green  plants 
of  types  IVg  and  Vic  (group  1,  table  39).  From  the  backcross  with  green 
of  type  IVg,  Ab  pi  R^,  five  major  color  types  appeared  and  both  the 
purple  and  the  sun  red  types  contained  subtypes  with  colored  and  with 
green  anthers.  While  all  the  classes  expected  from  an  F2  of  the  genotype 
A  A  Bb  PIpIR^  /  occurred,  the  frequency  distribution  was  so  far 
from  expectation  that  there  is  only  one  chance  in  five  hundred  that  the 
observed  deviations  may  have  been  due  to  errors  of  random  sampling,  P 
equaling  0.002.     The  expected  and  observed  distributions  are  as  follows: 

Color  types  Purple  Sun  red  ^'^"t^  ^'^''^^    Green     Total 

•^  ^  ^  purple  sun  red 

Ia,g      Ila,  g      Ilia      IVa   Illg,  IVg 

Observed 15  15  5  1  9  45 

Calculated 9  9  9  9  9  45 

Difference +6         +6        —4        —8  0  0 

Whether  the  discrepancy  is  genetically  significant  or  was  due  to  some  acci- 
dent of  pollination  cannot  now  be  determined.  A  backcross  of  the  same  F2 
plant  with  green  of  type  Vic,  ab  pi  /,  yielded  only  four  color  types,  as 
expected  (group  1,  table  39),  the  anthers  being  colored  in  all  cases.  The 
excess  of  purples  and  deficiency  in  two  other  classes  makes  the  deviations 
from  expectation  fairly  great,  so  that  there  is  only  about  one  chance  in 
seven  that  they  may  have  been  due  to  errors  of  random  sampling,  P 
equaling  0.14.     The  comparison  follows: 


92  R.  A.  Emerson 

Color  types                Purple   Sun  red  ^^^^  ^^       Total 

la           Ila  Ilia  IVa 

Observed 27             19  15  14                  75 

Calculated 19            19  19  19                  76 


Difference +8  0  —4  —5  —1 

A  third  purple-anthered  purple,  an  F-  plant  of  the  lot  regarded  as 
equivalent  to  Fo's,  gave  in  the  next  generation  purple-anthered  purples 
and  pink-anthered  sun  reds  in  the  relation  31:7  (group  2,  table  39).  From 
the  genotype  A  A  B  B  PI  pi  //,  these  two  phenotypes  should  appear 
in  a  3:1  ratio.  The  deviation  from  expectation  was  2.5  ±  1.8,  or  only 
such  as  might  be  expected  about  once  in  three  trials,  P  equaling  0.34. 

Two  green-anthered  purples  of  F2  and  two  of  the  equivalent  F3  lot 
noted  above  were  tested  by  a  later  generation.  Two  of  the  four  yielded 
three  color  tj^jes,  purple,  sun  red.  and  green,  all  with  green  anthers  (group  3, 
table  39).  Such  behavior  is  expected  from  the  genotype  A  A  B  b  PI 
pi  R^  R^.  The  9:3:4  relation  is  approached  so  closely  that  the  value 
of  P  cannot  be  determined  from  Pearson's  tables,  x^  equaling  0.36.  The 
comparison  follows: 

Color  types  Purple       Sun  red        Green  Total 


Purple 

Sun  red 

Green 

Ig 

Ilg 

Illg,  IVg 

37 

11 

14 

36 

12 

16 

Observed 37  11  14  62 

Calculated 36  12  16  64 

Difference +1  —1  —2  —2 

The  same  two  .green-anthered  purples  were  backcrossed  with  green 
of  type  IVg,  and  one  of  them  and  a  sib  of  the  other  with  green  of  tj-pe 
Vic,  with  results  as  shown  in  group  3  of  table  39.  The  crosses  with  type 
IVg,  AhplI^,  gave  the  same  three  classes  as  did  the  self-pollinations, 
and  the  frequency  distribution  differed  from  expectation  by  values  that 
might  occur  by  chance  about  once  in  two  trials,  P  equaling  0.49.  The 
comparison  follows: 


N  Maize 

93 

Sun  red 

Green 

Total 

Ilg 

nig,  ivg 

32 

53 

119 

30 

60 

120 

Color  types  Purple 

Ig 

Observed 34 

Calculated 30 

Difference +4  +2  —7  —1 

The  backcrosses  of  these  green-anthered  purples  with  green  of  type  Vic, 
a  b  pi  /,  as  was  to  be  expected,  gave  very  different  results.  There  were 
produced  four  instead  of  three  phenotypes,  all  with  colored  (purple  or 
pink)  instead  of  green  anthers.  The  deviations  from  the  theoretical 
frequency  distribution  are  such  as  might  be  expected  about  once  in  five 
trials,  P  equaling  0.21.     The  comparison  follows: 

Color  types 

Observed 

Calculated 


Purple 
la 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Total 

44 

44 

48 
44 

33 

44 

52 
44 

177 
176 

Difference 0  +4        —11  +8  +1 

The  other  two  green-anthered  purples  that  were  tested  yielded  only 
two  phenotypes,  green-anthered  purple  and  green,  in  the  relation  56:18 
(group  4,  table  39).  The  genotype  AABhPlPlRUi'  should  give 
these  two  phenotypes  in  a  3 : 1  ratio.  The  deviation  from  expectation 
was  therefore  0.5  ±  2.5.  One  of  the  same  plants  backci-ossed  to  green 
of  type  IVg  gave  28  green-anthered  purples  and  27  greens  where  equality 
was  expected. 

Of  the  twelve  kinds  of  behavior  expected  of  F2  purples  of  the  cross  of 
purple-anthered  purple  with  green  IVg,  only  four  have  been  demonstrated. 
So  far  as  they  go,  however,  the  results  are  quite  in  accord  with  the  hypoth- 
esis under  test.  In  addition  to  the  F2  purples,  sun  reds  and  dilute 
purples  also  were  tested  by  later  generations,  as  detailed  below. 

Three  pink-anthered  sun  reds  gave  sun  reds  and  dilute  sun  reds  only, 
all  with  pink  anthers  (table  40,  group  1).  These  three  plants  are  therefore 
regarded  as  A  A  Bh  pi  pi//.  The  ratio  observed  was  97:26.  The 
deviation  from  the  expected  3:1  ratio  was  4.75  it  3.24,  or  such  as  might 


94  R.  A.  Emerson 

occur  by  chance  once  in  three  trials,  P  equahng  0.32.  One  of  these  three 
sun  reds,  when  crossed  with  a  dilute  purple,  Ah  PI/,  gave  71  purples 
and  77  dilute  purples,  all  with  purple  anthers,  where  equal  numbers  were 
expected. 

Three  other  F2  pink-anthered  sun  reds  produced  nothing  but  sun  red 
plants  in  F3,  228  in  all  (group  2,  table  40).  Some  plants  of  each  progeny 
had  pink  and  some  had  green  anthers.  Small  plantings  of  each  lot  were 
made  in  the  garden  and  larger  plantings  in  the  field.  Anther  color  was 
noted  in  the  case  of  the  garden  plants  only.  The  records  show  44  with  pink 
and  16  with  green  anthers,  a  deviation  from  a  3: 1  ratio  of  only  1.0  ±  2.3. 
The  F2  sun  reds  are  therefore  assumed  to  have  been  A  A  B  B  plpl  R^  /. 
One  of  these  F2  plants  was  backcrossed  to  green,  both  of  type  IVg  and 
of  type  Vic,  resulting  in  a  total  of  108  sun  red  plants  (group  2).  Altho 
no  counts  were  made  for  anther  color,  it  was  noted  that  the  cross  with 
green  IVg,  Ah  pi  R^,  gave  both  pink-  and  green-anthered  plants,  while  the 
cross  with  green  Vic,  ah  pi  /,  gave  pink  anthers  alone.  Only  t'^^o  of  the 
six  possible  genotypes  of  F2  sun  reds  were  demonstrated. 

Only  one  dilute  purple  F2  plant  was  tested  further  (group  3,  table  40). 
From  self-pollination  it  yielded  46  dilute  purple  and  9  dilute  sun  red 
plants,  all  with  colored  (purple  or  pink)  anthers.  The  deviation  from 
a  3:1  ratio,  4.75  ±  2.17,  is  such  as  might  be  expected  by  chance  about 
once  in  seven  trials,  P  equaling  0.14.  The  same  F2  plant  when  back- 
crossed  to  green  of  types  IVg  and  Vic  (group  3)  gave  85  dilute  purples  and 
82  dilute  sun  reds  where  equality  was  expected.  Evidently  this  F2  was 
A  A  hh  Plplf  /. 

No  F2  dilute  sun  red  or  green  plants  were  tested  further.  One  F3 
dilute  sun  red,  however,  was  found  to  breed  true,  producing  an  F4  of  30 
pink-anthered  dilute  sun  reds.  Likewise,  eight  F3  and  F4  greens  gave 
a  total  of  126  green  plants  in  the  next  generation. 

In  so  far  as  tests  have  been  made,  therefore,  the  cross  of  purple-anthered 
purple  with  green  IVg  has  behaved  as  expected  on  the  basis  of  the  hypo- 
thetical genotype  assigned  to  Fi,  namely,  A  A  B  bPlplR^ /. 

Purple  Ig  x  green  I  Vg. —  Green-anthered  purples  are  assumed  to  be 
A  B  PI  R^,  and  green  IVg  to  be  A  6  pi  R^ .  The  Fi  genotype  is  therefore, 
theoretically,  A  A  B  b  PlplR^  R^,  and  F2  should  consist  of  the  three 
color  types  purple,  sun  red,  and  green,  all  with  green  anthers.  Eight 
such  F2  progenies  are  recorded  in  table  41,  group  1.     The  three  types 


Plant  Colors  in  Maize  95 

occurred  in  so  nearly  the  expected  relation  of  9:3:4  that  the  observed 
deviations  might  be  expected  by  chance  considerably  more  than  once  in 
three  trials,  P  cquahng  0.37.     The  comparison  follows: 

Color  types  Purple       Sun  red  Green  Total 

Ig  Ilg  Illg,  IVg 

Observed 293  105  150  548 

Calculated 308  103  137  548 

Difference —15  +2+13  0 

The  F2  greens  of  this  cross  are  assumed  to  consist  of  the  genotypes 
Ah  PI  R'  and  Abpl  R^,  which,  if  /  had  been  present  instead  of  R'^, 
would  have  been  dilute  purples  and  dilute  sun  reds,  respectively.  In 
substantiation  of  this  assumption,  crosses  of  Fi's,  all  green-anthered 
purples,  with  dilute  sun  red,  A  b  pi  /,  and  with  green  Vic,  ah  pi  /,  are 
recorded  in  group  2  of  table  41.  As  expected,  the  result  was  the  four 
classes  purple,  sun  red,  dilute  purple,  and  dilute  sun  red,  all  with  colored 
anthers.  The  expected  numerical  equality  of  the  four  classes  was  so 
closely  approached  that  deviations  such  as  those  observed  might  be 
expected  by  chance  in  nearly  three  out  of  four  trials,  P  equahng  0.74. 
The  comparison  follows: 

Color  types                        Purple  Sun  red  ^^^  ^^"^"^^^  Total 

la  Ila  Ilia  IVa 

Observed 58  61  62  70  251 

Calculated 63  63  63  63  252 

Difference —5  —2  —1  +7  — 1 

Still  another  Fi  was  crossed  with  a  pink-anthered  sun  red,  A  B  pi  /, 
and  gave  68  purples  and  67  sun  reds,  all  with  colored  anthers,  where 
equal  numbers  were  expected. 

So  far  as  tested,  therefore,  the  cross  of  green-anthered  purple  with 
green  IVg  has  given  the  results  expected  on  the  basis  of  the  hypothesis 
under  test. 

Purple  Ig  x  brown  V.—  A  cross  of  green-anthered  purple,  A  B  PIR^, 
with  brown,  a  B  PI  /,  gave  in  Fi  49  purple-anthered  purples,  presumably 

4 


96  R.  A.  Emerson 

A  aB  B  PI  PI  R^  /.  An  r2  progeny  was  grown  from  only  one  Fi  plant, 
6653-6,  resulting  in  two  major  color  types,  purple  and  brown,  in  approxi- 
mately a  3 : 1  ratio.  The  purples  were,  as  expected,  of  two  subtypes, 
one  with  purple  and  the  other  with  green  anthers.  The  theoretical  rela- 
tion of  9:3:4  was  realized  so  closely  that  the  observed  deviations  might 
be  expected  by  chance  in  at  least  two  out  of  three  trials,  x^  equaling  0.76 
(when   z'=l  and  n'  =  3,  P  =  0.61).     The  comparison  follows: 

Color  types.  f^^'P}?'  ^^'Plf  Brown  Total 

•^  ^  purple  anthers    green  anthers 

la  Ig  V 

Observed 23  5  9  37 

Calculated 21  7  9  37 

Difference +2  —2  0  0 

A  second  Fi  plant,  6653-2,  was  backcrossed  with  green  IVg,  Abpl  R^, 
resulting  in  39  purple  plants,  21  with  purple  and  18  with  green  anthers, 
where  equal  numbers  were  expected,  the  deviation  from  expectation  being 
1.5  ±  2.1.  The  same  Fi  plant  was  crossed  with  a  heterozygous  dilute 
sun  red,  A  abb  pi  pi  /  /,  resulting  in  45  purple-anthered  purples  and 
18  browns,  the  deviation  from  the  expected  3:1  ratio  being  2.25  db  2.32. 

Purple  Ig  x  dilute  purple  Ilia. —  Crosses  of  green-anthered  purple, 
A  B  PI  R^,  with  dilute  purple,  Ab  PI  /,  gave  in  Fi  purple-anthered 
purple,  A  A  B  b  PI  PI  R^  /.  The  F2  should  consist  of  purple-anthered 
and  green-anthered  purples,  dilute  purples,  and  greens,  the  three  major 
color  types  appearing  in  the  relation  12:3:1.  In  F2  from  a  single  Fi 
plant,  5263-3,  both  purple-anthered  and  green-anthered  purples  were 
noted,  but  detailed  counts  based  on  anther  color  were  not  made.  The 
deviations  from  the  expected  numbers  for  the  three  major  types  were 
such  as  might  occur  by  chance  in  nine  out  of  twenty  such  trials,  P  equaling 
0.45.     The  comparison  follows: 

Color  types                      Purple  ^^^\l  Green  Total 

la,  g  Ilia  Illg 

Observed 36                11                  5  52 

Calculated 39                10                  3  52 

Difference —3  +1  +2  0 


Plant  Colors  in  Maize  97 

A  second  Fi  plant  backcrossecl  with  green  IVg,  A  b  pi  R",  gave  the 
expected  four  types.  The  deviations  from  the  equal  frequency  expected 
for  the  several  types  was  such  as  might  occur  by  chance  somewhat  more 
than  once  in  four  trials,  P  equaling  0.27.     The  comparison  follows: 

Color             Purple,               Purple,  Dilute 

types       purple  anthers  green  anthers  purple 

la                    Ig  Ilia 

Observed...         59                    67  80 

Calculated..         71                    71  71 


Green 

Total 

Illg 

77 

283 

71 

284 

Difference..     —12  —4  +9  +6  — 1 

Dilute  purple  Ilia  x  green  IVg. —  A  single  cross  of  dilute  purple, 
Ah  PI  /,  with  green  I\'g,  A  b  pi  K',  gave  dilute  purple,  A  Abb  PI  pi  R^  /, 
in  Fi,  and  three  phenotypes,  dilute  purple,  dilute  sun  red,  and  green,  in 
F2  (table  42,  group  1,  page  150).  The  observed  frequencies  were  23 :8: 10, 
which  is  the  nearest  possible  approach  to  the  expected  9:3:4  relation  for 
a  total  of  41  individuals.  One  Fz-  dilute  purple  gave  similar  results  in  F3, 
indicating  the  same  genotype  as  the  Fi  dilute  purples.  The  F4  progenies 
of  this  F3  lot  may  be  regarded  as  equivalent  to  Fa's,  and  are,  therefore 
grouped  with  the  F3  in  table  43.  Three  F3  and  F4  progenies  (table  43, 
group  lA)  approached  the  9:3:4  relation  so  closely  that  the  observed 
deviations  might  occur  by  chance  in  nearly  three  out  of  five  trials,  P 
equaling  0.59.     The  comparison  follows: 

Color  types  ^^^^1^  ^^^t^.  Green  Total 

•^  ^  purple  sun  red 

Ilia  IVa         Illg,  IVg 

Observed 143  48  73  264 

Calculated 149  50  66  265 


Difference —6  —2  +7  —1 

The  green  plants  of  these  F3  and  F4  lots,  as  well  as  those  of  the  F2  lot 
listed  in  group  1  of  table  42,  are  assumed  to  be  Ab  Pi  R"  and  Abpl  R", 
and  consequently  to  differ  from  the  dilute  purples  and  dilute  sun  reds  only 
in  having  R'^  RF  in  place  of  R^  /  or  /  /.  That  the  R  r  pair  is  thus  con- 
cerned in  these  results  can  be  shown  ])y  a  comparison  between  the  plant- 


98  R.  A.  Emerson 

color  phenotypes  resulting  from  seeds  with  colored  aleurone  and  those 
from  seeds  with  colorless  aleurone.  The  Fo  progeny  came  from  a  plant 
that  produced  from  self-pollination  colored  and  colorless  seeds  in  the 
relation  60 :  24.  This  close  approach  to  a  3:1  ratio  indicates  that  the 
Fi  plant  could  have  been  heterozj^gous  for  only  one  of  the  aleurone-factor 
pairs  A  a,  C  c,  or  Rr  (Emerson,  1918).  A  cross  with  a  C  tester,  A  c  R, 
resulted  in  43  colored  and  no  colorless  seeds,  while  a  cross  with  an  R 
tester,  A  C  r,  gave  46  colored  and  32  colorless  seeds,  thus  indicating  R  r 
as  the  factor  pair  concerned.  The  colorless  seeds  must  therefore  have 
been  r  r,  presumabl}^  /  /,  and  in  accordance  with  the  hypothesis  under 
test  should  have  produced  no  gre^i  plants.  Some  of  the  colored  seeds, 
on  the  contrary,  should  have  been  R  R,  supposedly  R^  R^,  and  these 
should  have  given  green  plants.  For  the  most  part,  the  colored  and  the 
colorless  seeds  were  planted  separately.  The  9:3:4  relation  of  the  three 
plant-color  types  is  theoretically  made  up  of  a  6:2:4  relation  from  colored 
seeds  and  a  3:1:0  relation  from  colorless  seeds.  Actually,  from  colorless 
seeds  there  appeared  dilute  purple  and  dilute  sun  red  plants  in  the  ratio 
69:15.  The  deviation  from  expectation,  6.0  ±  2.7,  might  be  expected  to 
occur  about  once  in  seven  trials,  P  equaling  0.14.  From  colored  seeds 
the  deviation  from  the  theoretical  distribution  was  such  as  might  occur 
thru  errors  of  random  samphng  almost  once  in  four  trials,  P  equaling 
0.23.     The  comparison  follows: 


Dilute         Dilute 
sun  red 


Color  types  ^^^  *^ 

''  ^  purple 

Ilia  IVa 

Observed , 92  42 

Calculated 102  34 


Green 

Total 

Illg,  IVg 

70 

204 

68 

204 

Difference —10  4-8  +2  0 

Aleurone  is  in  some  cases  self-colored  and  in  some  cases  mottled. 
Mottled  aleurone  ordinarily  occurs  only  when  the  R  factor  is  heterozygous, 
but  not  all  heterozygous  individuals  are  mottled  (Emerson,  1918). 
Mottled  seeds  of  the  cross  under  discussion,  just  as  colorless  ones,  since 
they  are  presumably  R^  /,  should  produce  no  green  plants.  In  the 
case  of  some  of  the  progenies  noted  above,  the  colored  seeds  were  sorted 
into  self-colored,  mottled,  and  colorless.     Since  usually  about  one-third 


Plant  Colors  in  Maize  99 

of  the  colored  seeds  arc  mottled,  the  9:3:4  relation  of  plant-color  types 
observed  in  this  cross  should  be  made  up  of  a  3:1:0  relation  from  color- 
less seeds,  3:1:0  from  mottled  seeds,  and  3:1:4  from  self-colored  seeds. 
Of  the  progenies  for  which  the  seeds  were  sorted  in  this  way,  the  color- 
less seeds  produced  dilute  purple  and  dilute  sun  red  plants  in  the  relation 
60: 14,  with  a  deviation  from  3: 1  of  4.5  db  2.5,  the  mottled  seeds  gave  the 
same  plant-color  types  in  the  relation  30: 12,  with  a  deviation  of  1.5  ±  1.9, 
and  the  self-colored  seeds  yielded  dilute  purple,  dilute  sun  red,  and  green 
in  the  relation  48:19:64  (the  theoretical  distribution  for  a  total  of  131 
individuals  is  49:16:66),  the  deviations  being  such  as  might  occur  by 
chance  perhaps  three  times  in  four  trials,  z^  equaling  0.64.  On  the  whole, 
therefore,  these  crosses,  and  particularly  the  interrelations  of  aleurone  and 
plant  colors,  afford  strong  evidence  in  support  of  the  hypothesis  under  test. 
Before  presenting  further  F3  results  from  these  crosses,  it  may  be  well 
to  consider  other  crosses  of  dilute  purple  with  green  IVg  which,  so  far  as 
plant  color  alone  is  concerned,  have  given  results  quite  like  those  pre- 
sented above  but  which  exhibit  a  wholly  different  relation  between  plant 
color  and  aleurone  color.  The  green  plants  concerned  in  these  other 
crosses  were  C  testers  for  aleurone  color  (Emerson,  1918),  and  were  there- 
fore known  to  be  A  c  R,  presumably  A  c  B?.  The  dilute  purple  plants 
concerned  were  homozygous  for  aleurone  color,  and  were  consequently 
A  C  R,  presumably  A  c  R^.  These  crosses  differ,  then,  from  the  ones 
discussed  above  in  having  R^  in  place  of  r"  and  c  in  place  of  C.  Since  the 
C  c  pair  is  supposed  not  to  have  any  relation  to  plant  color,  the  results  for 
plant  color  should  be  quite  like  those  for  the  other  cross  and  there  should 
be  no  relation  between  plant  color  and  aleurone  color.  The  results  for 
F2  are  presented  in  table  42,  group  2,  and  the  F3  results  in  table  43, 
group  IB.  The  three  plant-color  types  appeared  in  F2  in  the  relation 
328:113:148,  and  in  F3  in  the  relation  40:14:23.  Considered  together 
these  lots  deviated  very  slightly  from  expectation,  x~  equaling  0.31.  The 
comparison  follows: 

Color  tvDes  ^^^"1^         ^'^"^'',         Green  Total 

»^oior  Types  purple         sun  red 

Ilia  IVa         Illg,  IVg 

Observed 368  127  171  666 

Calculated 375  125  166  666 

Difference —7  +2  -\-d  0 


100  R.  A.  Emerson 

The  seeds  from  which  these  plants  were  grown  consisted  of  colored  and 
colorless  in  approximately  a  3 : 1  ratio,  as  is  expected  when  the  C  factor 
alone  is  heterozygous.  The  deviations  from  the  expected  9:3:4  relation 
for  plants  from  colored  seeds  was  such  as  might  occur  by  chance  more  than 
once  in  three  trials,  P  equaling  0.36,  and  for  plants  from  colorless  seeds 
such  as  might  occur  once  in  six  trials,  P  equaling  0.17.  The  comparisons 
follow : 

Plant-color  types  ^^^        ^J^^^        Green  Total 

Ilia  IVa  Illg,  IVg 
Colored  seeds: 

Observed 215  58  89                  362 

Calculated 204  68  90                  362 

Difference +11  —10  —1  0 

Colorless  seeds: 

Observed 65  32  32  129 

Calculated 73  24  32  129 

Difference —8+8  0  0 

The  resvilts  presented  for  plant  color  alone  and  in  relation  to  aleurone 
color  in  these  crosses  are  therefore  quite  in  keeping  with  the  hj'^pothetical 
constitution  assigned  to  the  Fi  plants,  namely,  AAhhPlplKR'Cc, 
just  as  the  results  from  the  other  crosses  were  in  keeping  with  the  assumed 
genotype  AAbhPlplR'/CC  for  their  Fi  plants. 

A  single  Fi  plant  was  backcrossed  with  green  IVg,  Ah  pi  R\  with 
results  as  shown  in  table  42,  group  3.  The  three  color  types  dilute  purple, 
dilute  sun  red,  and  green,  occurred  in  the  relation  46:45 :  86.  The  expected 
distribution  for  a  total  of  177  individuals  is  44:44:89,  showing  almost  a 
perfect  fit,  x-  equaling  0.21. 

For  both  the  lots  of  crosses  under  discussion,  further  tests  are  afforded 
by  the  behavior  in  F3  and  F4.  As  already  shown,  some  of  the  F2  dilute 
purples  had  the  same  genetic  constitution  as  the  Fi  plants  (table  43, 
groups  lA  and  IB).  The  progenies  of  two  other  dilute  purples,  one  of 
F2  and  the  other  of  an  equivalent  F,-?,  produced  dilute  purple  and  dilute 
sun  red  plants  only  (group  2,  table  43),  in  the  relation  82:23.     The  devia- 


Plant  Colors  in  Maize  101 

tion  from  a  3:1  ratio  is  3.25  ±  2.99.  From  their  behavior  and  in  viow 
of  the  crosses  in  which  they  occurred,  one  of  these  plants  is  assumed  to 
have  been  A  Abb  PI  pi  /V  and  the  other  A  Abb  PI  pi  R'  R\ 

A  single  dilute  purple  of  an  F?  lot  equivalent  to  an  F2  gave  dilute  purple 
and  green  plants  only  (group  3,  table  43).  The  two  color  types  appeared 
in  the  ratio  62:16,  a  deviation  from  3:1  of  3.5  ±  2.6.  The  Fj  plant  is 
therefore  assumed  to  have  been  A  Abb  PI  PI  R"  /.  Colorless  and 
mottled  seeds  produced  dilute  purple  plants  only,  as  was  expected.  From 
self-colored  seeds  there  resulted  dilute  purple  and  green  plants  in  the 
relation  26:16,  a  deviation  of  2.0  ±  2.0  from  the  expected  2:1  ratio. 

Two  dilute  sun  red  plants  gave  progenies  of  dilute  sun  reds  and  greens 
in  the  relation  63:22,  a  deviation  from  a  3:1  ratio  of  0.75  ±  2.69  (group 
4,  table  43).  Presumably  these  plants  were  A  Abb  pi  pi  R"/  and 
A  Abb  pi  pi  R''  R^.  Four  other  dilute  sun  red  plants  bred  true  in  the 
next  generation  (group  5,  table  43),  producing  a  total  of  197  dilute  sun 
red  plants.  These  plants  are  therefore  assigned  the  genotype  A  Abb  pi 
pi  /  /. 

Seven  green  plants  likewise  bred  true  (group  6,  table  43),  producing  a 
total  of  130  green  plants.  These  plants  were  presumably  Abpl  R^  and 
AbPl  R\ 

To  summarize,  all  types  of  behavior  were  observed  in  F3  and  equivalent 
F4  generations  of  the  cross  of  dilute  purple  with  green  IVg  except  true- 
breeding  dilute  purples.  Only  eight  dilute  purples  were  tested,  and  only 
one  in  nine  is  expected  to  breed  true. 

Sun  red  11  g  and  11  a  and  dilute  sun  red  IV a  x  green  Illg  and  IVg. —  Two 
crosses  of  green-anthered  sun  red  with  green  IVg  gave  green-anthered 
sun  red  plants  in  Fi,  theoretically  A  A  B  b  j)l  pi  R'  R^.  The  parent 
types  only  appeared  in  F2  (table  44,  group  1).  The  observed  numbers 
of  green-anthered  sun  reds  and  greens  were,  respectively,  216  and  77. 
The  deviation  from  the  expected  3:1  ratio  was  3.7  5zb  5.00. 

A  cross  of  pink-anthered  sun  red  with  green  IVg  gave  pink-anthered 
sun  red  in  Fi,  theoretically  A  A  Bbplpl  R^  /.  Fi  plants  backcrossed 
with  green  IVg,  A  b  pi  R\  gave  three  major  plant-color  types  (group  2, 
table  44)  —  sun  red,  dilute  sun  red,  and  green  —  with  the  sun  reds  appear- 
ing in  two  subtypes,  one  pink-anthered  and  the  other  green-anthered. 
Theoretically  the  four  types  should  have  been  represented  by  an  equal 
number  of  individuals.     The  deviations  from  this  expectation  were  such 


102  R..  A.  Emerson 

that  there  is  considerably  more  than  an  even  chance  that  they  might 
have  been  due  to  errors  of  random  sampHng,  P  equaling  0.56.  The 
comparison  follows: 

^  1      ,                    Sun  red,           Sun  red,           Dilute      ^ rr„+„i 

Color  types       pi^k  anthers    green  anthers      sun  red     ^'^^^  ^^^^^ 
Ila                   Ilg                 IVa          IVg 

Observed 105                   90                  105          109  409 

Calculated 102                  102                  102          102  408 

Difference +3  —12  +3  +7  +1 

Crosses  of  dilute  sun  red  with  green  IVg  gave  54  dilute  sun  red  plants  in 
F],  A  A  hhplplR^  /.  In  F2  (group  3,  table  44)  there  resulted  from  a 
self-pollinated  Fi,  dilute  sun  red  and  green  plants  in  the  relation  55:22, 
a  deviation  from  the  expected  3:1  ratio  of  2.75  ±  2.56.  An  Fi  back- 
crossed  with  green  IVg  gave  the  same  two  color  types  in  equal  numbers, 
30  each,  exactly  as  expected.  Numerous  other  crosses  of  this  sort  have 
been  observed  in  connection  with  studies  of  the  interrelations  of  aleurone- 
color  and  plant-color  factors.  Since  these  data  are  to  be  presented  in  a 
later  paper  and  since  they  are  wholly  in  accord  with  the  data  given  in 
group  3  of  table  44,  they  are  not  discussed  here. 

In  an  earlier  section  of  this  paper  dealing  with  the  factor  pairs  A  a, 
B  b,  and  PI  pi  only  (page  29),  it  was  shown  that  the  green  plants  there 
noted  are  of  three  kinds,  namely,  abpl,  a  B  pi,  and  a  b  PL  Thruout 
the  present  section  of  the  paper,  which  deals  with  the  relation  of  the 
multiple-allelomorph  series  containing  R",  r\  K^  r\  it  has  been  assumed 
that  plants  which  in  the  presence  of  /  or  R^  are  dilute  purple  or  dilute 
sun  red,  are  green  in  the  presence  of  homozygous  R^.  The  data  presented 
are  wholly  in  accord  with  this  interpretation,  thereby  giving  considerable 
assurance  of  the  probable  correctness  of  the  hypothesis.  The  reported 
interrelations  of  plant  color  and  aleurone  color  when  the  latter  was  known 
to  involve  the  R  r  pair,  have  still  further  strengthened  this  assurance.  It 
remains  now  to  present  even  more  direct  evidence,  namely,  that  obtained 
from  crosses  of  green  plants  encountered  in  this  study,  with  sun  red  and 
dilute  sun  red  plants.  These  green  plants  are  assumed  to  be  A  6  PI  R^, 
type  Illg,  and  Abpl  R\  type  IVg. 

Certain  F3  and  F4  progenies  consisting  of  green-anthered  purples  and 
greens  in  a  3: 1  relation  are  listed  in  table  39,  group  4.     These  green  plants 


Plant  Colors  in  Maize  103 

were  all.  presumably,  A  b  PI  /?".  Green  plants  of  a  later  generation, 
grown  from  these  greens,  when  crossed  with  sun  red  plants,  type  Ila,  gave 
64  purple-anthered  purples  and  no  other  types  (table  45,  group  1). 
Another  green  crossed  with  dilute  sun  red  resulted  in  4  dilute  purples. 
Obviously  the  same  results  would  have  been  obtained  had  the  green  plants 
used  in  these  crosses  been  ah  Plr^,  instead  of  A  6  P/  7^"  as  they  are  sup- 
posed to  have  been.  As  a  matter  of  fact,  however,  one  of  these  green 
plants  had  homozygous  colored  aleurone,  and  therefore  must  have  been 
A  C  R.  The  other  two  greens,  while  they  had  colorless  aleurone,  came  from 
lots  known,  from  their  3:1  aleurone-color  ratios  and  from  crosses  with 
aleurone  testers,  to  be  heterozygous  for  C  alone,  and  therefore  A  c  R. 
Moreover,  the  green  plants  from  lots  consisting  of  purples  and  greens  in  a 
3 : 1  relation  could  not  have  been  a  a,  for  the  parents  of  such  lots,  if  hetero- 
zygous for  A,  must  have  produced  purples  and  browns  rather  than  purples 
and  greens.  The  green  plants  could  therefore  have  been  nothing  other 
than  A  b  PI  R'. 

Similarly,  progenies  consisting  of  green-anthered  purples  and  sun  reds, 
and  greens,  in  a  9:3:4  relation,  are  hsted  in  table  39,  group  3.  Green 
plants  of  these  lots  and  their  green  descendants  might  be  either  Ab  PIR^ 
or  A  b  pi  R",  or  might  be  heterozygous  for  PL  Six  such  green  plants  were 
crossed  with  dilute  sun  reds  (table  45,  group  2).  None  of  these  greens 
could'have  been  of  the  types  discussed  in  the  earlier  section  of  this  paper, 
namely,  ah  PI/  and  the  like,  for  they  were  shown  b}^  appropriate  tests 
(Emerson,  1918)  to  he  A  c  R  and  some  of  them  have  even  been  used  as 
C  testers  for  aleurone  color.  Two  of  these  green  plants  crossed  with  dilute 
sun  reds  gave  dilute  sun  reds  only,  59  in  all,  and  are  consequently  regarded 
as  being  Ah  pi  R^.  Two  others  by  sunilar  crosses  gave  dilute  purples 
and  dilute  sun  reds  in  the  relation  20:30,  a  deviation  of  5.0  ±2.4  from  the 
expected  equality  from  plants  of  the  genotype  A  Abb  PI  pi  R"  R". 
Two  other  greens  were  crossed  with  heterozygous  dilute  sun  reds, 
A  Abb  pi  pi  R'^  /,  and  gave  dilute  purples,  dilute  sun  reds,  and  greens 
in  the  relation  69:54:106.  The  theoretical  distribution  among  these 
three  classes  for  a  total  of  229  individuals,  based  on  the  assumption  that 
the  green  parent  plants  were  A  Abb  Pi  pi  R"  R\  is  57:57:115,  a  devia- 
tion that  might  occur  by  chance  about  once  in  five  trials,  P  equaUng  0.19. 

Progenies  consisting  of  dilute  purples,  dilute  sun  reds,  and  greens  in  a 
9:3:4  relation  are  listed  in  table  43,  group  lA.     Descendants  of  one  of 


104  R.  A,  Emerson 

these  green  plants  were  crossed  with  dilute  sun  reds  which  were  Fi's  of 
crosses  between  dilute  sun  red  and  green  IVg.  The  results  were  dilute 
purple  and  green  plants  in  the  relation  328:338  (table  45,  group  3),  a 
deviation  from  a  1 : 1  ratio  of  5.0  ±  8.7.  Since  the  heterozygous  dilute 
sun  red  plants  were  A  Ah  h  pi  pi  R^  /,  the  green  plants  crossed  with  them 
are  assumed  to  have  been  A  b  PI  R^.  That  this  assumption  is  correct 
appears  the  more  evident  from  the  fact  that  the  green  plants  were  homo- 
zygous for  colored  aleurone,  and  hence  A  C  R. 

Green  IVg  x  green  Vic. —  Twelve  crosses  between  green  plants  of  type 
IVg  and  green  plants  of  type  Vic  gave  a  total  of  159  Fi  plants,  all  dilute 
sun  red.  With  respect  to  aleurone  color,  all  the  type  IVg  plants  concerned 
in  these  crosses  were  known  to  be  A  c  R,  and,  in  fact,  were  in  general 
use  as  C  testers  for  aleurone  color.  With  respect  to  plant  color,  therefore, 
they  are  assigned  the  constitution  Ahpl  R^.  Of  the  type  Vic  greens, 
four  were  known  to  be  A  testers  for  aleurone  color,  and  were  therefore, 
with  respect  to  aleurone  color,  a  C  R.  Their  plant-color  constitution  is 
accordingly  set  down  as  ahpl  R^.  Six  of  the  type  Vic  greens  had  an 
aleurone-color  constitution  of  aC  r,  their  plant-color  genotype  being 
accordingly  ahpl  /.  The  other  two  Vic  greens  were  certainly  a  b  pi, 
but  whether  they  were  R'^  or  /  is  unknown. 

In  Fa,  dilute  sun  red  and  green  plants  were  present  in  the  ratio  420:291 
(table  46,  group  1,  page  154).  From  an  Fi  of  the  genotype  A  ahh  pi  pi 
plus*  R^  /  or  R^  R^,  a  9 : 7  ratio  of  dilute  sun  red  to  green  is  to  be  expected 
in  F2,  since  both  A  and  /  or  R^  are  assumed  to  be  necessary  for  the  pro- 
duction of  anthocyanic  pigment,  which  distinguishes  dilute  sun  red  from 
green.  The  theoretical  ratio  for  a  total  of  711  individuals  is  400:311. 
The  observed  deviation  from  this  ratio,  20.0  ±  8.9,  is  such  as  might 
occur  by  chance  about  once  in  eight  trials,  P  equaling  0.13. 

Two  Fi  plants  backcrossed  to  green  Vic,  a  h  pi  R^,  gave  66  dilute  sun 
red  and  58  green  plants,  and  two  backcrosses  with  green  IVg,  A  h  pi  r^, 
gave  96  dilute  sun  reds  and  96  greens,  equality  of  the  two  classes  being 
expected  in  the  case  of  both  crosses  (group  2,  table  46). 

That  the  two  parent  types  of  green  occurred  in  F2  is  shown  by  their 
relations  to  aleurone  and  pericarp  color.  In  the  case  of  every  cross,  green 
plants  were  produced  from  both  colored  and  colorless  seeds.  Those 
from  colored  seeds  could  have  been  only  A  h  pi  R^.  Since  some  seeds 
were  colorless  because  of  a  a  and  some  because  of  c  c,  both  parent  types  of 
green  should  have  been  present  in  the  lots  grown  from  colorless  seeds. 


Plant  Colors  in  Maize  105 

In  one  cross  there  was  prosont  tho  pericarp  factor  P,  which  with  A  gives  a 
red  and  with  n  a  a  l)rown  pericarp.  All  the  F2  green  plants  from  colored 
seeds  had  red  pericarp,  and  of  those  from  colorless  seeds  the  majority  had 
brown  pericarp.  From  the  colorless  seeds  there  should  have  occurred 
also  a  conil)ination  type  of  green,  a  b  pi  W,  but  no  tests  were  made  for 
the  identification  of  this  type. 

Ten  dilute  sun  reds  of  F-  were  tested  by  their  F3  behavior.  Three 
of  these  (table  47,  group  1)  gave  dilute  sun  red  and  green  plants  in  the 
relation  108 :  77,  a  deviation  from  a  9 : 7  ratio  of  4.0  ±  4.6.  Five  other 
F2  plants  (group  2)  gave  the  two  color  types  in  the  relation  187:66,  a  devia- 
tion from  a  3 : 1  ratio  of  3.0  ±  4.6.  Two  F2's  (group  3)  bred  true  dilute 
sun  red,  producing  78  dilute  sun  red  and  no  green  offspring.  Theoretically, 
of  9  Fo  dilute  sun  reds,  there  should  occur  in  F3,  true-breeding,  3:1, 
and  9:7  progenies  in  the  numerical  relation  1:4:4,  The  observed  rela- 
tion between  these  three  sorts  of  l^ehavior  for  the  ten  F2's  tested  was 
2:5:3.  Deviations  such  as  these  might  occur  by  chance  about  once  in 
two  trials,  P  equaling  0.49. 

Green  IVg  x  green  Via. —  Certain  crosses  of  green  IVg  with  green  \I 
have  given  sun  red  plants  in  Fi.  The  t^^pe  VI  greens  belonged  to  families 
in  which  the  B  factor  was  known  to  be  present.  They  were  therefore 
doubtless  a  B  pi  plus  /  or  R\  and  the  Fi's  were  probably  A  a  B  b  pi  pi 
plus  /  R^  or  R"  R^.  F2  consisted  of  the  three  major  color  t^'pes  sun  red, 
dilute  sun  red,  and  green  (table  48,  group  1)  in  the  relation  586:161:348. 
Obviously  this  is  not  a  9 : 3 : 4  relation,  for  the  deviations  from  such  expecta- 
tion, -30,  -44, +74,  could  not  be  expected  to  occur  thru  errors  of  random 
sampling  once  in  a  million  such  trials,  z^  equaling  30.9  and  P  equaling 
.000000+.  As  a  matter  of  fact,  an  Fi  of  the  genotype  suggested  above 
should  give  in  F2  the  three  color  types  observed  in  the  relation  36:9:19. 
The  observed  frequencies  of  the  several  classes  fit  this  expectation  so 
closely  that  the  deviations  from  it  might  occur  by  chance  in  about  one 
out  of  five  trials.  P  equaling  0.19.  The  comparison  of  observed  and 
expected  frequencies  follows: 

Color  types  Sun  red       g^^^  ^.^^  Green        Total 

Ila,  g  IVa       IVg,  Via,  c 

Observed 586  161  348  1 ,095 

Calculated 616  154  325  1 .095 

Difference —30  +7  +23  0 


106  R.  A.  Emerson 

Not  only  were  the  frequencies  of  the  major  color  types  fairly  close  to 
expectation,  as  indicated  above,  but  the  expected  subclasses  of  sun  red  with 
pink  anthers  and  with  green  anthers  were  observed.  Counts  of  anther 
color  were  made  -in  the  case  of  only  65  individuals.  These  plants  were 
distributed  to  the  four  color  classes,  pink-anthered  sun  red,  green-anthered 
sun  red,  dilute  sun  red,  and  green,  in  the  order  24:9:10:22.  The 
theoretical  distribution  of  64  individuals  being  27:9:9:19,  the  deviations 
are  such  as  might  occur  by  chance  perhaps  twice  in  three  trials,  z^  equaling 
0.91  (when  x^  =  1  and  n'  =  3,  P  =  0.61). 

Only  three  Fa  sun  reds  were  tested  in  F3.  One  of  them  (group  2,  table  48) 
bred  true  sun  red,  but  segregated  with  respect  to  anther  color.  It  was  there- 
fore presumably  A  A  B  B  pi  pi/  R''.  Two  other  F2  sun  reds  (group  3) 
gave  sun  red  and  green  offspring  in  the  ratio  229:71,  a  deviation  of  only 
4.0  ±  5.1  from  a  3:1  ratio.  One  of  these  two  F2  plants  was  crossed 
with  a  dilute  sun  red,  resulting  in  55  sun  red  plants.  The  two  F2  plants, 
therefore,  were  presumably  A  a  B  B  pi  pi.  Anther  color  was  not  deter- 
mined, but  the  fact  that  the  green  plants  of  F3  all  came  from  colorless 
seeds  is  conclusive  evidence  for  the  presence  of  4  a  and  against  the  pres- 
ence of  /  R^.  The  genotype  of  the  F2  plants  is  accordingly  set  down  as 
AaBBplpl  / /. 

Green  Illg  x  green  Vic. —  Green  plants  known  to  be  of  type  Vic,  ah  pi  /, 
were  crossed  with  greens  which  were  known  to  be  R^  R^  and  which  from 
their  parentage  might  have  had  Pi.  The  result  in  Fi  was  dilute  purple, 
supposedly  A  ah  h  PI  pi  f  R^.  Two  F2  lots  (table  49,  group  1)  consisted 
of  dilute  purples,  dilute  sun  reds,  and  greens  in  the  relation  109 :  37 :  135. 
From  the  assumed  genotype  of  Fi,  there  should  occur  in  F2  the  observed 
color  types  in  the  relation  27:9:28.  The  observed  frequencies  deviated 
from  the  theoretical  ones  by  amounts  such  as  might  occur  by  chance 
once  in  three  trials.  P  equaling  0.33.     The  comparison  follows: 

ri  1     2.  Dilute 

Color  types  ^^^^^^^ 

Ilia 

Observed 109 

Calculated 119 

Difference —10  —3  +12  — 1 


Dilute             ^ 
sun  red            ^'^^^" 

Total 

IVa      Illg,  IVg,  Ylb,  c 

37                  135 

281 

40                  123 

282 

Plant  Colors  in  Maize  107 

The  dilute  purples  of  F2  were  presumably  all  A  b  PI  /  and  the  dilute 
sun  reds  all  A  b  pi  /.  Of  the  Fo  greens  there  should  theoretically  have 
been  six  types,  namely,  AbPlR^,  AbplR",  abPl/,  ah  pi/,  ah  PIP?, 
and  a  b  pi  R^.  The  relation  of  these  plant  colors  to  aleurone  color  and 
to  a  pericarp  color  known  as  cherry,  present  in  these  families,  affords  an 
opportunity  of  checking  some  of  these  hypothetical  formulae.  Cherry 
pericarp  is  a  bright  reddish  purple,  somewhat  variable  in  intensity.  In 
the  parent  of  one  of  these  F2  progenies  it  was  sufficiently  light  to  make 
possible  the  determination  of  the  underlying  aleurone  color.  The  F2  seeds 
consisted  of  colored  and  colorless  aleurone  in  the  ratio  140:171,  a  devia- 
tion from  a  27:37  ratio  of  9.0  ±  5.9,  or  such  a  deviation  as  might  occur 
by  chance  three  times  in  ten  trials,  P  equaling  0.30.  The  Fi  plants  were 
known  to  be  AaRr,  and  in  order  to  give  a  27:37  ratio  with  respect 
to  aleurone  color  they  must  have  been  also  C  c.  Cherry  pericarp  is  of 
such  a  nature  that  it  never  develops  except  in  the  presence  of  PI.  With  A 
and  PI  it  is  cherry,  but  with  a  and  PI  it  is  brownish.  It  had  been  regarded 
by  the  writer  as  due  to  a  factor,  Ch,  but  recently  Dr.  E.  G.  Anderson  has 
shown  (by  unpublished  data)  that  the  writer's  Ch  is  apparently  another 
allelomorph  of  R,  and  at  present  it  is  known  to  exist  only  in  the  form  /^. 
Since  all  dilute  purples  of  the  lots  under  consideration  here  are  assumed 
to  be  A  6  PI  f^,  they  should  all  have  cherry  pericarp.  Again,  since  dilute 
sun  reds  are  pi  pl,  they  should  all  have  colorless  pericarp.  Furthermore, 
since  all  green  plants  from  colored  seeds  are  supposed  to  be  R^  R^,  their 
pericarp  should  likewise  be  colorless.  Finally,  since  the  colorless  seeds 
may  lack  color  because  of  either  a  a,  r  r,  or  c  c  alone,  or  because  of  both 
a  a  and  r  r,  some  green  plants  from  colorless  seeds  should  have  color- 
less pericarp,  a  R^  or  A  c  R",  and  some  should  have  brownish  pericarp, 
a  PI  /^.  Of  course  all  green  plants  with  pl  pl  also  must  have  colorless 
pericarp. 

The  observed  results  are  whoUy  in  accord  with  these  suppositions.  In 
one  F2  progeny,  pericarp  color  was  determined  for  all  except  a  few  plants. 
From  seeds  with  colored  aleurone,  all  the  dilute  purples  had  cherry  peri- 
carp and  all  the  dilute  sun  reds  and  greens  had  colorless  pericarp.  These 
three  classes  of  plant  and  pericarp  color  showed  frequencies  deviating  from 
the  theoretical  27:9:18  relation  by  quantities  such  as  might  occur  by 
chance  almost  once  in  four  trials,  P  equaling  0.23.  From  seeds  with 
colorless  aleurone,  all  dilute  purples  had  cherry  pericarp,  all  dilute  sun 


108  R.  A.  Emerson 

reds  had  colorless  pericarp,  and  greens  had  in  part  brownish  and  in  part 
colorless  pericarp.  The  deviations  from  the  expected  27 : 9 :  18 :  20  relation 
of  these  four  color  classes  were  such  as  might  occur  thru  errors  of  random 
sampling  in  more  than  seven  out  of  any  ten  such  trials,  P  equaling  0.72. 
The  comparisons  follow: 


Plant  color 

Dilute 
purple 

Dilute 
sun  red 

Green 

Green 

Total 

Pericarp  color 

Cherry 

Colorless 

Brownish 

Colorless 

Ilia 

IVa 

VIb 

Illg,  IVg,  Vic 

Colored  aleurone: 

Observed.  .  .  . 

43 

10 

0 

35 

88 

Calculated . .  . 

44 

15 

0 

29 

88 

Difference.-. . 

—1 

—5 

0 

+6 

0 

Colorless  aleurone: 

Observed.  .  .  . 

38 

11 

32 

28 

109 

Calculated . . . 

40 

13 

27 

29 

109 

Difference .  . . 

—2 

—2 

+5 

—1 

0 

Further  tests  of  the  factorial  composition,  with  respect  to  PI,  of  some 
F2  green  plants  of  this  cross  are  afforded  by  crosses  between  them  and  sun 
red  and  dilute  sun  red  plants.  One  F2  green  crossed  with  sun  red  gave 
27  purple  plants  (table  49,  group  2).  Since  the  green  parent  plant  came 
from  a  colored  seed,  it  is  assumed  to  have  been  PI  PI  R^  BF  plus  A  A  ov 
A  a.  Two  other  greens  crossed  with  dilute  sun  red  gave  39  dilute  purple 
plants,  and  were  therefore  PI  PI  (group  2,  table  49).  Since  one  of  these 
green  plants  had  brownish  and  the  other  had  colorless  pericarp,  they  are 
assumed  to  have  been  also  f^  and  R'  W,  respectively.  A  fourth  F2 
green  crossed  with  sun  red  gave  purple  and  sun  red  plants,  and  a  fifth 
green  crossed  with  dilute  sun  red  gave  dilute  purple  and  dilute  sun  red 
plants,  indicating  Plyl  (group  3,  table  49).  The  first  of  these  two  had 
brownish  and  the  second  had  colorless  pericarp.  They  must  therefore 
have  been  r'^''  and  I^  W,  respectively.  A  sixth  F2  green  crossed  with 
dilute  sun  red  gave  only  dilute  sun  red  plants,  and  so  must  have  been 
yl'pl  (group  4). 


Plant  Colors  in  Maize  109 

Green  Illg  x  green  Via. —  In  the  soctioiis  immodiatoly  preceding  this, 
it  has  been  shown  that  intercrosses  of  greens  may  give  dilute  sun  reds 
(page  104),  dikite  purples  (page  106),  or  sun  reds  (page  105)  in  Fi,  the 
particular  color  type  depending  on  the  genotypes  of  the  greens  chosen 
for  crossing.  It  remains  to  be  shown  that  purple  la  can  be  produced  ])y 
intercrosses  of  gre'ens.  A  cross  of  green  Via,  aBplY,  with  green  Illg, 
Ah  PI  R\  should  give  this  result,  Fi  being  AaBb  PlplR'  /.  Such 
a  cross  has  been  made,  with  results  as  expected. 

A  stock  of  green  plants  was  isolated  from  a  cross  of  brown  V,  a  B  PI  /, 
with  green  VIc,  a  h  pi  /,  and  was  shown,  by  crosses  with  aleurone  testers 
and  with  dilute  sun  red  IVa,  to  be  type  Via,  a  B  pi  /.  Another  lot  of 
greens  arose  from  a  cross  of  purple  Ig  with  green  IVg.  The  purple  Ig 
parent  was.  from  a  lot  consisting  of  purple  la,  purple  Ig,  dilute  purple 
Ilia,  and  green  Illg,  coming  from  a  cross  of  purple  Ig  with  dilute  purple 
Ilia  heterozygous  for  R^  /.  It  was  therefore  AABhPlPlR^  W. 
The  green  IVg  plant  with  which  it  was  crossed  was  known  to  be  A  6  pi  RF. 
The  Fi  of  this  cross  consisted,  as  was  expected,  of  purples  and  greens  only. 
The  purples  were  type  Ig  and  must  have  been  heterozygous  for  B  b  and 
PI  pi,  and  the  greens  must  have  been  type  Illg  and  heterozygous  for 
PI  pl,  or  A  Abb  PI  pi  R^  RF.  Two  of  these  Fi  greens  were  crossed  with 
one  of  the  greens  of  tj^pe  Via  mentioned  above.  The  two  crosses,  9659 
and  9660,  resulted  as  expected  in  purple-anthered  purples,  type  la,  and 
pink-anthered  sun  reds,  type  Ila,  in  the  relation  18:20.  It  has  been 
demonstrated,  therefore,  that  by  crossing  wholly  green  plants  of  appro- 
priate genotypes  it  is  possible  to  produce  purple-anthered  purples,  the 
most  highly  colored  type  known,  a  type  that  is  dominant  to  all  other 
types. 

Green  Illg  x  purple  la. —  A  green  plant  with  homozygous  purple  aleurone 
and  belonging  to  a  family  (table  39,  group  4)  consisting  of  green-anthered 
purples  and  greens  only,  and  therefore  theoretically  being  A  b  PI  R^, 
was  crossed  with  a  purple-anthered  purple,  A  B  PI  /.  A  purple-anthered 
purple  Fi,  A  A  Bb  PI  PI  f  R",  5350-9,  was  backcrossed  with  green  IVg 
of  the  genotype  A  b  pl  ?■",  with  the  result  that  in  the  next  generation 
there  appeared  four  color  types,  purple-anthered  purple,  green-anthered 
purple,  dilute  purple,  and  green,  in  the  relation  28:22:21:29.  The 
deviations  from  the  expected  equal  distribution  of  the  100  individuals 
were  such  as  might  occur  by  chance  in  considerably  more  than  half  of 


110  R.  A.  Emerson 

such  trials,  P  equaling  0.57.  It  will  be  recalled  that  results  like  these 
were  obtained  from  a  cross  of  green-anthered  purple  with  dilute  purple 
(page  96),  and  of  course  the  same  results  were  to  be  expected  since  the  Fi 
in  both  cases  is  supposed  to  have  been  A  A  B  b  PI  PI  /R^. 

The  cross  now  under  consideration  has  interest  from  the  standpoint  of 
the  relation  of  aleurone  color  to  plant  color,  and  also  for  certain  hnkage 
relations.  The  Fi  was  known  to  be,  with  respect  to  aleurone  color, 
A  A  Rr.  Whether  it  was  C  C  or  C  c  was  not  known,  since  a  strong  red 
pericarp  made  aleurone  counts  impracticable.  The  green  plant  on  which 
the  Fi  was  backcrossed,  was  determined  by  appropriate  tests  to  be  C  C, 
so  that  the  relation  of  the  Fi  purple  to  C  is  immaterial.  The  backcross 
resulted  in  approximatelj'-  equal  numbers  of  seeds  with  and  without 
aleurone  color,  there  being  109  colored  and  110  colorless  seeds.  The 
colorless  seeds  must  have  been  A  B  C  PI/  t^  and  Ah  C  PI/  7^,  and 
should  therefore  have  produced  purple-anthered  purples  and  dilute  purples 
only;  while  the  colored  seeds  must  have  been  A  B  C  PI  R"  /  and  Ah  C 
PI  R^  r^,  and  should  correspondingly  have  produced  green-anthered 
purples  and  greens  only.  The  results  were  quite  in  accord  with  expecta- 
tion, as  is  shown  in  the  following  comparison: 

Green      Total 

Illg 

29  51 

0  49 

It  has  been  shown  earlier  in  this  paper  (page  63)  that  a  linkage  exists 
between  the  factor  pair  B  h  and  a  factor  pair,  Lg  Ig,  for  normal  or  ligule- 
less  leaf,  the  percentage  of  crossing-over  being  about  30.  It  happens 
that  the  Fi  of  this  cross  was  Lg  lg  as  well  as  B  h,  B  lg  having  come  from 
one  parent  and  h  Lg  from  the  other,  and  that  the  green  plant  used  in  the 
backcross  was  h  lg.  There  is  no  question  here  that  the  purple-anthered 
purples  and  dilute  purples  produced  from  colorless  seeds  differed  with 
respect  to  the  B  h  pair  only.  Their  linkage  with  liguleless  leaf,  as  indi- 
cated by  the  percentage  of  crossing-over,  was  29.4,  or  a  deviation  from 
30  of  0.6  ±  2.0.  Practically  the  same  linkage  relation  was  found  for  the 
plants  from  colored  seeds,  green-anthered  purples  and  greens.  In  this 
case  the  percentage  of  crossing-over  was  27.5,  a  deviation  from  30  of 


Color  types 

Purple, 
purple  anthers 

Purple, 
green  anthers 

Dilute 
purple 

la 

lg 

Ilia 

Colored  seeds.  .  .  . 

0 

22 

0 

Colorless  seeds .  .  . 

28 

0 

21 

Plant  Colors  in  Maize  111 

2.5  ±2.1,  or  such  as  might  occur  by  chance  about  twice  in  five  trials, 
P  equahng  0.42.  It  is  to  be  assumed,  therefore,  that  the  same  difference 
exists  between  green-anthered  purples  and  greens  as  between  purple- 
anthered  purples  and  dilute  purples,  namely,  a  difference  with  respect 
to  the  factor  pair  B  b.  This  in  turn  is  merely  additional  evidence  that 
plants  which  in  the  presence  of  /  are  dilute  purples,  A  b  PI,  appear  as 
greens  in  the  presence  of  R"  r",  which  is  the  hypothesis  under  test  thruout 
this  section  of  the  paper. 

Purple  la  x  green-anthered  dilute  sun  red 

A  purple-anthered  purple,  known  from  appropriate  aleurone-color 
tests  to  he  R  R  and  hence  A  B  PI  R^,  was  crossed  with  a  dilute  sun  red 
which  differed  from  most  dilute  sun  reds  in  showing  much  less  anthocyanic 
pigment,  particularly  in  early  stages  of  growth,  than  is  usual  in  plants  of 
that  type,  and  in  having  little,  if  any,  color  in  its  anthers.  The  F/s, 
2975,  were  purple-anthered  purples.  F2  was  expected  to  show  the  four 
color  types,  purple,  sun  red,  dilute  purple,  and  dilute  sun  red,  commonly 
found  in  crosses  of  purple  la  with  dilute  sun  red  IVa.  As  a  matter  of 
fact,  the  single  F2  progeny  grown  was  found  to  consist  of  these  four  color 
types  as  major  classes,  but  each  class  was  found  to  have  colored-anthered 
(purple  or  pink)  and  green-anthered  subclasses.  The  difference  between 
the  two  subclasses  for  purple  and  sun  red  was  sharp,  just  as  is  the  case 
in  crosses  of  purple  la  with  green  IVg,  but  it  was  often  difficult  to  separate 
green-anthered  dilute  purples  from  green-anthered  dilute  sun  reds. 
Ordinarily,  anther  color  (purple  or  pink)  is  the  surest  means  of  distinguish- 
ing between  dilute  purple  and  dilute  sun  red.  When  both  have  green 
anthers  the  separation  must  be  based  on  the  relative  amount  of  pigment 
in  other  plant  parts  —  a  difference  that  is  usually  not  very  marked  until 
late  in  the  life  of  the  plants,  when  dilute  purples  usually  show  materially 
more  pigment,  especially  in  parts  not  exposed  to  the  sun,  than  do  dilute 
sun  reds.  It  will  be  recalled  that  in  crosses  of  purple  la  with  green  IVg, 
both  colored  and  green-anthered  purples  and  sun  reds  appear,  but  that 
all  the  dilute  purples  and  dilute  sun  reds  have  colored  anthers,  the  green- 
anthered  individuals  appearing  as  wholly  green  in  all  plant  parts  except 
perhaps  the  pericarp.  But  in  the  cross  here  considered,  no  wholly  green 
plants  were  found. 


112 


R.  A.  Emerson 


The  natural  supposition  is  that  there  is  here  concerned  still  another 
form  of  the  R  factor,  such  that,  while  it  does  not  allow  color  to  develop 
in  the  anthers,  does  nevertheless  result  in  the  development  of  some  antho- 
cyanic  pigment  in  other  parts  of  the  plant.  The  dilute  sun  red  plant  used 
as  one  parent  of  this  cross  was  found  to  he  A  c  R  with  respect  to  alcurone. 
The  factor  particularly  concerned  in  the  behavior  here  reported  is  there- 
fore assigned  the  designation  R''^.  The  Fi  plants  are  accordingly  assumed 
to  have  been  A  A  Bb  Plpl  R''  R^^.  The  frequency  distribution  for  the 
eight  color  types  observed  in  F2  approached  the  theoretical  distribution 
so  closely  that  deviations  of  the  magnitude  observed  might  occur  by  chance 
nearly  three  times  in  any  ten  such  trials,  P  equaling  0.72.  The  com- 
parison follows: 

x~\:i.,4-«       T^cii,*-^       T^,*i,,+«         T^;i,,4-« 

Total 


491 
491 


Plant  color 
Anther  color 

Purple 
Purple 

Purple 
Green 

Sun  red 
Pink 

Sun  red 
Green 

Dilute 
purple 
Purple 

Dilute 
purple 
Green 

Dilute 

sun  red 

Pink 

Dilute 
sun  red 
Green 

Observed. .  . 
Calculated . 

212 
207 

77 
69 

66 
69 

22 
23 

60 
09 

23 
23 

22 
23 

3 

8 

Difference. .       +5 


+8  —3  —1  —3 


0 


0 


One  F2,  a  green-anthered  purple,  was  tested  in  F3.  This  plant  bred 
true,  producing  128  green-anthered  purples  and  no  other  types. 

It  is  unfortunate  that  the  relation  of  aleurone  color  to  plant  color  in 
this  cross  afforded  no  check  on  the  assumption  that  the  observed  behavior 
with  respect  to  anther  color  of  dilute  purples  and  reds  was  due  to  a  factor 
belonging  to  the  allelomorphic  series  R^,  R^,  /,  r^.  True,  the  Fi  plant 
tested  was  heterozygous  with  respect  to  aleurone  color,  but  this  was 
known  to  be  due  to  C  c.  Since  no  further  tests  have  been  made,  the  only 
evidence  in  support  of  the  assumption  of  a  factor  R^^  is  the  very  close 
fit  of  observed  with  theoretical  frequency  distributions,  the  fact  that  colored 
and  green  anthers  in  purple  and  sun  red  types  of  many  other  crosses  have 
been  found  to  be  due  to  the  R  factor,  and  the  demonstrated  presence  of 
R  in  the  green-anthered  sun  red  plant  used  in  the  cross. 


,0    jch 


Summary  of  results  involving  the  allelomorphic  series  R^,  R^,  R^^,  1,1,1 

Crosses  of  brown  with  green  of  type  IVg  have  been  shown  to  result 
in  purple  Fi's,  and  in  eight  color  types  in  F2  in  a  numerical  relation  approxi- 
mating 81:27:27:9:27:9:36:40,  or  in  six  major  color  types,  anther  color 
being   disregarded,    in    approximately    the   relation    108:36:27:9:36:40. 


Plant  Colors  in  Maize  113 

It  has  been  noted  that  these  results  are  wholly  unhke  those  for  crosses  of 
brown  with  green  reported  in  an  earher  section  of  this  paper,  and  are 
similar  in  general,  tho  with  marked  differences  in  detail,  to  previously 
discussed  crosses  of  brown  with  dilute  sun  red.  As  an  interpretation  of 
these  results,  it  has  been  assumed  that,  in  addition  to  the  three  pairs 
A  a,  B  b,  PI  2)1,  a  fourth  pair  —  members  of  a  multiple-allelomorph 
series,  such  as  R^  Bf,  /  R",  or  R^  i^  —  is  concerned.  It  has  been  assumed 
further  that  R^  or  /  is  necessary  ordinarily  for  the  development  of  dilute 
purple  and  dilute  sun  red  and  for  the  appearance  of  purple  and  pink 
anthers  in  purples  and  sun  reds,  respectively,  while  /i"  R°  or  r''  r^  is 
necessary  for  green  anthers  of  purples  and  sun  reds  and  for  the  con- 
version of  dilute  purples  and  dilute  sun  reds  into  wholly  green  plants. 
Smiilarly,  the  appearance  of  green-anthered  dilute  purples  and  dilute 
sun  reds  in  a  single  cross  has  been  ascribed  to  R^^  R^^.  The  relation  of 
the  R  allelomorph  to  both  aleurone  color  and  plant  color  has  afforded 
rehable  tests  of  the  hypothesis.  Other  tests  have  consisted  of  the 
behavior  in  later  generations  of  the  several  F2  color  types  and  the  results 
of  intercrosses  between  these  types.  Neither  of  these  tests  has  been  carried 
to  the  point  of  exhausting  all  the  possibilities,  but  in  all  a  considerable 
number  of  tests  have  been  made  and  all  have  given  results  in  support  of 
the  hypothesis.  A  single  linkage  test,  involving  the  B  b  pair  with  leaf 
type,  Lg  Ig,  has  afforded  added  support.  On  the  whole,  therefore,  the 
hypothesis  haS  been,  if  not  substantiated,  at  least  rendered  highly  probable. 

RELATION  OF  ALEURONE  FACTORS  C  C    AND  Pr  pr    TO  PLANT  COLOR 

The  relations  of  the  aleurone  factors  A  and  R  to  plant  color  have  been 
noted  repeatedly  in  this  account.  A  single  observation  suggests  a  rela- 
tion between  the  aleurone-f actor  pair  C  c  and  leaf  color.  Culture  2909 
came  from  colored  seeds  of  a  selfed  ear  showing  a  3 : 1  ratio  of  colored  to 
white  seeds,  and  therefore  heterozygous  for  a  single  pair  of  aleurone-color 
factors.  Several  ears  in  the  resulting  progeny  also  gave  3 : 1  ratios.  Tests 
of  four  plants  with  aleurone  testers  gave  conclusive  evidence  that  the 
C  c  pair  was  the  one  concerned.  One  selfed  plant  of  the  lot,  2909-32, 
had  318  colored  and  105  white  seeds.  Both  the  colored  and  the  white 
seeds  produced  only  sun  red  plants,  some  with  green  and  some  with  pink 
anthers,  indicating  the  genotype  A  A  B  BC  cplpl  W  R^.  All  the  plants 
showed  strong  sun  red  pigment  in  the  sheaths  and  the  outer  husks,  but 


114  R.  A.  Emerson 

there  was  distinctly  more  red  color  in  the  leaves  of  the  plants  from  colored 
seeds  than  in  the  leaves  of  the  plants  from  white  seeds.  Particular  atten- 
tion has  not  been  given  to  a  possible  effect  of  the  C  factor  on  mature  plant 
colors  of  other  color  types.  Many  cultures  of  dilute  sun  reds  and  greens 
have  afforded  opportunities  for  observing  any  effect  of  C  and  c  on  red  color 
in  the  leaves  of  seedlings,  but  no  effects  have  been  noted.  No  particular 
attention  was  paid  to  the  matter  at  the  time  when  the  seedlings  were  under 
observation,  but  if  the  C  c  pair  had  exerted  any  marked  influence  it  would 
probably  have  been  noted. 

Numerous  cultures  of  dilute  sun  red  seedlings  have  been  noted  with 
respect  to  possible  effects  of  the  aleurone-factor  pair  Pr  pr,  but  no  effect 
has  been  observed,  the  purple  and  the  red  seeds  having  produced  seedlings 
with  apparently  the  same  intensity  of  red  color.  Likewise,  no  influence  of 
Pr  pr  on  mature  plant  color  has  ever  been  observed  in  the  case  of  either 
sun  red  or  dilute  sun  red.  With  purple  and  dilute  purple  plants,  however, 
a  distinct  effect  is  noticeable.  Purple  and  dilute  purple  plants  from  seeds 
with  purple  aleurone  have  purple  anthers,  while  those  from  seeds  witJi 
red  aleurone  have  reddish  purple  anthers  (Plate  I,  1  and  3,  and  Plate 
II,  1  and  3).  A  similar  effect  is  often  seen  also  in  the  color  of  the  inner 
husks.  In  neither  the  anthers  nor  the  husks  is  the  effect  always  suffi- 
ciently distinct  to  make  possible  an  accurate  separation  of  plants  from 
purple  and  from  red  seeds  if  they  are  growing  in  mixed  cultures.  In 
some  cases,  however,  the  difference  is  very  distinct.  And  when  the 
seeds  are  separated  with  respect  to  purple  and  red  aleurone,  the  two  lo+s 
of  plants  resulting  usually  show  fairly  distinct  differences  in  anther  color 
and  often  in  husk  color  as  well. 

EXPRESSION    OF    PLANT-COLOR   AND    ALEURONE- COLOR   FACTORS 

The  mode  of  expression  of  the  several  plant-color  factors  has  been  dis- 
cussed in  detail  in  this  paper,  and  similar  discussions  of  aleurone-color 
factors  are  available  in  numerous  other  papers.  Since  aleurone  colors 
and  certain  plant  colors  —  the  purple-red  series  —  are  doubtless  antho- 
cyanins,  it  seems  natural  to  expect  close  interrelations  between  them. 
Many  such  relations  have  been  noted  in  this  account.  There  are  certain 
matters,  however,  which  need  to  be  brought  together  in  a  summary 
discussion. 


Plant  Colors  in  Maize  115 

It  will  be  recalled  (Emerson,  1918)  that  for  the  development  of  any 
aleurone  color,  the  presence  of  three  dominant  factors,  A,  C,  and  R, 
and  also  of  a  duplex  recessive  factor  pair,  i  i,  is  necessary.  The  Pr  pr 
pair  has  no  visible  expression  except  when  associated  with  this  combination 
of  the  other  factors,  and  then  it  determines  whether  the  color  shall  be 
purple  or  red.  So  far  as  is  now  known,  the  plant-color  situation  with 
respect  to  complementary  factors  is  not  quite  so  complex.  Something  of 
the  same  sort  is  seen,  however,  in  the  fact  that  no  anthocyanic  pigment 
ordinarily  develops  except  either  in  the  presence  of  A  and  R"",  /,  or  r"'', 
or  in  the  presence  of  A,  B,  and  R^  R^  or  r^ /.  With  the  first  of  these 
combinations,  the  pairs  B  h  and  PI  pi  determine  the  particular  color 
type  of  the  purple-red  series.  Two  of  these  types,  purple  and  dilute 
purple,  are  modified  further  by  Pr  pr,  and  the  intensity  of  their  color 
depends  also  on  the  member  of  the  R  series  present,  r'^'^  exerting  a  more 
pronounced  effect  than  R''  or  /.  One  type  at  least,  sun  red,  is  influenced 
somewhat  by  C  c.  With  the  second  combination.  A,  B,  and  R^  R''  or 
r^  r",  the  pair  PI  pi  determines  whether  the  type  shall  be  purple  or  sun 
red.  For  the  formation  of  the  non-anthocyanic  (flavonol)  pigment,  brown, 
the  interaction  of  a  a  with"  either  B  or  PI  is  essential,  and  usually  very 
little  color  develops  except  when  both  B  and  PI  are  present.  Brown  is 
made  more  intense  by  the  presence  of  /*. 

Of  the  factors  concerned  with  plant  colors  of  maize,  the  A  a  pair  is 
one  of  the  most  fundamental,  since  it  differentiates  sharply  the  antho- 
cyanins  of  the  purple-red  series,  A  B  PI,  A  B  pi,  Ah  PI,  A  b  pi,  from 
the  non-anthocyanic  brown,  aBPl,  and  the  slightly  brown  or  green 
a  B  pi  and  ab  PI  and  the  wholly  green  a  b  pi.  Without  A  no  anthocyanin 
shows  in  either  the  aleurone  or  the  other  parts  of  the  plant.  A  second 
fundamental  pair  is  Pi  pi,  which  differentiates  the  sun  colors  from  those 
that  develop  in  local  darkness.  Purple  (A  B  PI),  dilute  purple  (A  b  Pi), 
and  brown  (a  B  PI)  are  all  able  to  .develop  in  darkness;  while  sun  red 
(ABpl),  dilute  sun  red  (Abpl),  and  the  slight  brown  sometimes  seen 
in  a  B  pi,  do  not  develop  except  in  the  presence  of  light.  Whether  or  not 
the  slight  brown  sometimes  present  in  a  6  Pi  forms  in  darkness  has  not 
been  determined.  To  the  Pr  pr  pair  is  due  a  definite  qualitative  difference 
in  the  colors  formed  which  is  presumably  associated  with  a  difference  in 
chemical  composition  of  the  pigments.  In  the  presence  of  Pr  aleurone 
color  is  purple,  and  with  pr  it  is  red,  and  a  similar  difference,  tho  not  always 


116  R.  A.  Emerson 

so  sharp  a  one,  is  seen  in  the  effects  of  Pr  pr  on  the  anther  and  husk  color 
of  purples  and  dilute  purples.  The  factors  R^  and  r^  on  the  one  hand, 
both  recessive  with  respect  to  plant  color,  and  R^  and  /  on  the  other 
hand,  both  dominant  for  plant  color,  apparently  alwaj'S  differentiate 
between  colored  and  colorless  anthers  and  silks  in  the  purple-red  series 
of  plant  colors,  and,  when  B  is  absent,  determine  whether  or  not  antho- 
cy.anin  forms  in  any  part  of  tlie  plant.  The  pair  B  h  influences  mainly  the 
intensity  of  pigmentation.  Thus,  purple,  A  B  PI,  is  more  strongly 
colored  than  is  weak  purple,  A  B^  PI,  which  in  turn  is  more  strongly 
colored  than  is  dilute  purple,  A  b  PL  The  same  relation  holds  between 
sun  red,  A  B  pi,  weak  sun  red,  A  B^  pi,  and  dilute  sun  red,  A  b  pi.  Brown 
color  shows  very  little  in  ab  PI  but  is  strongly  developed  in  a  5  PL 
A  similar  difference,  however,  exists  between  the  slight  brown  of  a  B  pl 
and  the  full  brown  oi  a  B  PL  In  the  one  case  in  which  an  effect  of  C  c 
has  been  noted,  C  acted  as  an  intensifier  of  color. 

There  are  som.ewhat  marked  differences  between  the  several  factor 
pairs  with  respect  to  the  stage  of  plant  development  at  which  their  influence 
is  expressed.  Seedlings  of  purple,  sun  red,  dilute  purple,  and  dilute  sun 
red  normally  exhibit  no  characteristic  differences  in  intensity  or  extent 
of  pigmentation.  The  B  b  and  PI  pl  pairs,  which  differentiate  these 
color  types  so  sharply  at  a  later  stage  of  growth,  do  not,  therefore,  come 
into  expression  early.  All  of  these  types  are  more  highly  colored  late 
in  their  growth  period  than  they  are  as  seedlings,  but  the  later  changes 
are  much  more  pronounced,  for  instance,  in  dilute  purple  than  in  dilute 
sun  red,  and  somewhat  more  so  in  purple  than  in  sun  red.  Apparently, 
Pl  exerts  its  influence  comparatively  late,  but  under  the  intensifying 
influence  of  B,  even  Pl  expresses  itself  fairly  early. 

The  several  factor  pairs  differ  more  or  less  with  respect  to  the  particular 
plant  parts  affected.  Differences  in  the  expression  of  B,  B^,  and  b  are 
more  apparent  in  the  husks  and  the  sheaths,  particularly  the  upper  sheaths, 
than  elsewhere.  When  plants  of  the  genotype  a  B  pl,  common^  classed 
as  green,  show  any  brown,  the  color  is  limited  to  the  sheaths  and  the 
outer  husks.  The  difference  between  purple  (A  B  Pl)  and  sun  red  {A  B  pl) 
on  the  one  hand,  and  dilute  purple  (A  b  Pl)  and  dilute  sun  red  (A  b  pl) 
on  the  other,  is  more  pronounced  in  the  husks  and  the  sheaths  than 
elsewhere.  Little  difference  is  apparent  between  the  two  groups  with 
respect  to  the  color  of  anthers,  glumes,  silks,  and  the  like.     The  pair 


Plant  Colors  in  Maize  117 

PI  pi  is  perhaps  expressed  most  definitely  in  the  color  of  anthers,  tho 
the  expression  is  by  no  means  limited  to  them.  Puiple  {A  B  PI)  and 
dilute  purple  {A  b  PI)  differ  from  sun  red  (A  B  pJ)  and  dilute  sun  red 
(A  hpl),  not  merely  in  having  purple  rather  than  pink  anthers,  but  also 
in  the  coloration  of  their  inner  husks,  their  culms,  and  the  like.  What 
little  brown  color  is  seen  in  ab  PI  is  limited  almost  wholly  to  the  staminate 
inflorescence.  The  staminate  inflorescence  of  purples,  A  B  PI,  and  of 
browns,  a  B  PI,  is  strongly  colored,  but  that  of  dilute  purple,  A  b  PI, 
except  for  anther  color,  is  not  very  different  from  what  is  seen  in  dilute 
sun  red,  A  b  pi.  The  PI  factor,  when  associated  with  r"^^,  is  expressed 
in  the  pericarp  as  cherry  in  purple  and  in  dilute  purple,  and  as  brownish 
in  brown  and  in  green  of  the  genotype  a  b  PL 

Factors  B  b  and  PI  pi  are  not  known  to  be  concerned  with  aleurone 
color.  All  the  other  factors  affecting  plant  color  are  aleurone-color 
factors  also.  Of  these  the  pair  Pr  pr  influences  anther  color  of  purple 
and  dilute  purple,  and  to  some  degree  the  husk  color  as  well.  The  pair 
C  c  has  been  observed  to  affect  the  leaf  color  of  mature  plants  of  the 
sun  red  type.  The  pair  A  a  is  expressed  to  some  degree  in  all  such  parts 
as  culms,  sheaths,  husks,  glumes,  anthers,  and  silks.  The  pericarp, 
if  a  pericarp  factor  P  is  present,  is  red  with  A  and  brown  with  a,  or  if  r'^'^ 
and  Pi  are  present,  it  is  cherry  with  A  and  brownish  with  a.  The  R 
series  of  factors  influences  many  plant  parts.  With  duplex  R^  or  r^, 
no  color  develops  in  any  part  of  the  plant,  except  the  aleurone,  provided 
B  is  absent.  With  B  these  factors  give  colorless  anthers  and  silks  merely. 
Factors  K^  and  /,  if  A  also  is  present,  affect  practically  all  plant  parts 
in  which  anthocyanic  pigments  ever  develop,  but  are  not  iknown  to 
have  any  influence  on  the  color  of  the  pericarp.  The  factor  r'^^  is,  how- 
ever, concerned  with  pericarp  color  provided  PI  also  is  present.  This 
factor  has  a  marked  influence  on  the  amount  of  color  that  forms  in  the 
leaves,  particularly  of  dilute  purple  and  dilute  sun  red. 

It  is  of  no  little  interest  that  the  R  series  of  factors,  which  behaves 
as  a  group  of  multiple  allelomorphs  with  regard  to  plant  color,  usually 
acts  as  a  simple  pair  in  respect  to  aleurone  color.*  Moreover,  some  of 
these  factors  act  as  dominants  with  respect  to  aleurone  color  and  as 
recessives  with  respect  to  plant  color,  while  the  dominance  of  others  is 

«  There  is'^some  evidence  that  at  least  one  aleurone-color  pattern  is  dependent  on  an  allelomorph   of 
R  r,  the  three  thus  constituting  a  group  of  triple  allelomorphs  affecting  aleurone-color  development. 


118  R.  A.  Emerson 

the  reverse  of  this.  For  example,  r"  and  r"''  are  recessive  for  aleurone 
and  dominant  for  plant  color,  and  R^  is  dominant  for  aleurone  and 
recessive  for  plant  color,  while  R'^  is  dominant  and  r^  recessive  for  both 
alem-one  and  plant  colors. 

SUMMARY 

In  this  account,  six  major  plant-color  types  of  maize,  purple,  sun  red, 
dilute  purple,  dilute  sun  red,  brown,  and  green  (colorless),  together  with 
the  subtj^pes,  weak  purple,  weak  sun  red,  green-anthered  purple,  green- 
anthered  sun  red,  and  five  genotypes  of  green,  are  described  and  illustrated, 
and  their  environmental  and  genetic  relations  are  discussed. 

The  sun  red  and  dilute  sun  red  types  are  shown  to  be  dependent  on 
Hght  for  the  development  of  their  color,  while  the  purple,  dilute  purple, 
and  brown  types  develop  their  characteristic  colors  in  darkness. 
Diversities  of  temperature  and  of  soil  moisture  are  shown  to  have  no 
direct  effect  on  the  formation  of  maize  plant  colors  but  to  have  an  indirect 
relation  to  them  thru  their  influence  on  soil  fertility,  which  in  turn  bears 
a  definite  relation  to  the  development  of  the  purple-red  series  of  plant 
color,  anrthocyanins,  but  little  or  no  relation  to  brown.  Sun  colors 
particularly  are  shown  to  be  markedly  intensified  by  infertile  soil.  It  is 
noted  that  the  several  types  of  the  purple-red  series  are  sharply 
differentiated  when  grown  on  fertile  soil,  but  that  their  characteristic 
differences  are  largely  masked  by  growth  on  infertile  soil,  while  the 
brown-green*  series  is  most  readily  distinguished  from  the  purple-red 
series,  especially  in  the  seedling  stage,  if  grown  on  infertile  soil.  It  is 
suggested  that  the  effect  of  infertile  soil  may  be  due  to  a  deficiency  of 
nitrogen,  and  perhaps  of  phosphorus.  Observations  indicating  a  close 
connection  between  the  accumulation  of  carbohydrates  and  strong  colora- 
tion are  reported,  and  the  inference  that  the  effect  of  infertile  soil  is 
brought  about  thru  checking  growth  without  inhibiting  photosynthesis, 
thus  allowing  an  accumulation  of  carbohydrates,  is  discussed. 

In  an  attempt  at  a  genetic  analysis  of  the  several  plant-color  types, 
data  accumulated  during  a  period  of  some  ten  years,  and  involving  an 
examination  of  approximately  680  progenies  and  not  less  than  48,000 
individual  plants,  are  reported.  As  an  interpretation  of  the  results 
obtained  from  the  more  complex  crosses,  the  allelomorphic  pairs  A  a 
and  PI  j)l,  and  the  multiple  allelomorphs  B,  B"",  b\  h,  and  R\  R\  R'\ 


Plant  Colors  in  Maize  119 

/,  r*,  r*^,  are  assumed  and  genetic  formulae  are  assigned  to  the  several 
color  types  as  follows:  purple,  A  B  PI;  sun  red,  A  B  pi;  dilute  purple, 
Ab  PI;  dilute  sun  red,  Abpl;  brown,  a  B  PI;  green,  a  B  j^,  ah  PI,  ah  pi; 
all  these  having  in  addition  R\  /,  or  r"^.  The  factor  i^''"  is  assumed 
to  be  the  causal  factor  for  green  anthers  and  silks  in  purple,  sun  red, 
dilute  purple,  and  dilute  sun  red  types,  and  W  and  r''  are  assumed  to  have 
the  same  effect  on  purple  and  sun  red  and  to  insure  colorlessness  (green 
type)  thruout  in  what  would  otherwise  be  dilute  purple  and  dilute  sun  red, 
the  R  series  having  no  effect  on  brown,  except  for  r'^'',  which  intensifies 
brown  as  well  as  purple  and  dilute  purple.  Of  the  R  scries,  R^  is  dominant 
and  1^  is  recessive  for  both  plant  and  aleurone  color,  f  and  r'^^  are  dominant 
for  plant  and  recessive  for  aleurone  color,  R^  is  recessive  for  plant  and 
dominant  for  aleurone  color,  and  R''^  is  dominant  for  aleurone  color  and 
also  for  plant  color  except  of  the  anthers  and  the  silks,  for  which  it  is 
recessive.  The  A  a  pair  is  concerned  with  both  aleurone  and  plant  color, 
and  the  aleurone  pairs  C  c  and  Pr  pr  are  assumed  to  exert  a  modifying 
effect  on  certain  plant  colors. 

The  principal  hypotheses  involved  are  shown  to  be  in  keeping  with 
observed  facts  when  subjected  to  practically  all  the  available  genetic 
tests,  such  as  backcrosses  of  Fi  with  multiple  recessives,  behavior  of  F2 
types  in  later  generations,  intercrosses  of  the  several  F2  types,  relation 
of  aleurone  color  to  plant  color,  linkage  of  certain  plant-color  types  with 
normal-  and  liguleless-leaf  types  and  of  other  plant-color  types  with 
yellow  and  white  endosperm.  Approximately  32  per  cent  of  crossing- 
over  is  reported  between  B  h  and  Lg  Ig  and  about  20  to  30  per  cent  between 
PI  pi  and  Y  y. 


120  R.  A.  Emerson 


LITERATURE  CITED 

Collins,  G.  N.     Gametic  coupling  as  a  cause  of  correlations.     Amer. 
nat.  46:569-590.     1912. 

CzARTKOwsKi,     Adam.       Authocyanbildung     und    Aschenbestandteile. 
Deut.  bot.  Gesell.     Ber.  32:407-410.     1914. 

East,  E.   M.,  and  Hayes,  H.  K.     Inheritance  in  maize.     Connecticut 
Agr.  Exp.  Sta.     Bui.  167: 1-142.     1911. 

Emerson,  R.  A.     Genetic  correlation  and  spurious  allelomorphism  in  maize. 
Nebraska  Agr.  Exp.  Sta.     Ann.  rept.  24:58-90.     1911. 

The    inheritance    of    the    ligule    and    auricles   of    corn  leaves. 


Nebraska  Agr.  Exp.  Sta.     Ann.  rept.  25:81-88.     1912. 

A  fifth  pair  of  factors,  A  a,  for  aleurone  color  in  maize,  and  its 

relation   to   the   C  c   and   R  r   pairs.     Cornell   Univ.    Agr.    Exp.   Sta. 
Memoir  16:225-289.     1918. 

Gernert,  W.  B.  The  analysis  of  characters  in  corn  and  their  behavior 
in  transmission,  p.  1-58.  (Published  by  the  author,  Champaign, 
Illinois.)     1912. 

Knudson,  Lewis.  Influence  of  certain  carbohvdrates  on  green  plants. 
Cornell  Univ.  Agr.  Exp.  Sta.     Memou-  9:1-75.     1916. 

LiNDSTROM,  E.  W.  Chlorophyll  inheritance  in  maize.  Cornell  Univ. 
Agr.  Exp.  Sta.     Memoir  13 : 1-68.     1918. 

Sando,  Charles  E.,  and  Bartlett,  H.  H.  The  occurrence  of  quercetin 
in  Emerson's  brown-husked  type  of  maize.  Journ.  agr.  research.  1921. 
(In  press.) 

Webber,  Herbert  J.  Correlation  of  characters  in  plant  breeding. 
Amer.  Breeders'  Assoc.  2:73-83.     1908. 

Wheldale,  M.  On  the  formation  of  anthocyanin.  Journ.  genetics 
1:133-158.     1911. 


Memoir  .3^,  A  Modified  Babcock  Method  for  Determining  Fat  in  Butter,  the  second  preceding  number  in 
this  series  of  publications,  was  mailed  on  December  10,  1920. 


Plant  Colors  in  Maize 


121 


APPENDIX 

TABLE  1.     Fi  Progenies  of  Purple  la  x  Green  VTc 


Pedigree  nos. 

Number  of 

Pi 

Fi 

1 1  plants 
(Purple  la) 

724-1  X    722-1 

857 

IS 

1121-8x1122-7 

1420,  1512,  2022. 

40 

1122-5  X  1121-2 

1419,  1511.   . 

36 

1525-5  X  1546-5 

20.56 

17 

Total,  4  progenies 

111 

TABLE  2.     F2  Progenies  of  Purple  la  x  Green  Vie 


Pedigree  nos. 

Number  of  F2  plants 

Group 

Fi 

Fo 

Purple 
la 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

smi  red 

IVa 

Brown 
V 

Green 
Via,  b,  c 

1 

1419-  1.. 
1511-  1.. 
1512-12. 
2022-  3.. 
2056-  6.. 

-11.. 
-16.. 

1513 

2018 

2020 

4012,4013. 
2415,  2416, 

42.84 

2417,  2418, 
2553-2559, 
4001-1007. 
2412,  4066, 

4067 

94 
61 
54 

7 

39 

96 
17 

22 

19 

16 

6 

13 

22 
3 

26 

13 

23 

6 

17 

24 
11 

12 

4 
7 
3 

4 

3 

1 

20 

13 

21 

4 

16 

26 
8 

23 
9 

7 
1 

10 

8 
7 

Total,  7  progenies 

36S 

101 

120 

U 

108 

65 

2 

1514-24.. 

-31 
2000-  8. . 
2019-28. 

-34.. 

2906-  1 . . 

2907-  1 .  . 

-  7.  , 

2981-  2. 

-  5 
4020-  7 
4032-  1 

-  3 

-  4. 

20.54 

2055 

2419,4065 

4281 

4282 

5303 

5290-5293. 

7050, 7051 
5299,  5300, 

70.54,  7055 
.50)6,  5067 . 
5068,  5069 
.5712,6810 

.5739 

50!^ 

5087 

20 
22 
92 
24 
21 
17 

93 

105 
17 

20 
10<) 
16 
15 
13 

7 
4 
29 
8 
6 
7 

26 

46 
4 
6 

44 
5 
/ 
5 

8 
4 
21 
4 
4 
5 

34 

30 
5 
2 

26 
3 
5 
4 

1 
2 

8 
0 

4 
2 

7 

10 
1 
1 

12 
2 

4 
1 

5 
2 

19 
4 

7 
6 

34 

38 
8 
2 

31 
3 
4 
7 

2 
6 
25 
6 
4 
3 

23 

31 
3 
3 

33 
2 
3 
7 

Total,   14  progenies .... 

5^ 

204 

155 

57 

170 

151 

Total,  21  progenies 

952 

305 

275 

91 

278 

216 

122 


R.  A.  Emerson 


TABLE  3.    F''  Progenies  of  Purple  x  Green  Backcbossed  with  Geeen 
(la  X  Vic)  X  Vic 


Pedigree  nos. 

Number  of  F2  plants 

Group 

Fi  X  Vic 

F2 

Purple 
la 

Sun 
red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Brown 
V 

Green 
Via, 
b,  c 

1 

1420-  1x1430-  3 
1511-  1x1516-  1. 
1512-12 X         -14. 
2056-16x1995-  6. 

1514 

2019 

2021 

2413, 4068 

12 

18 

23 

4 

19 

8 

18 

10 

15 

12 
16 
8 

16 
8 

10 
6 

14 

18 

13 

8 

45 
50 
44 
18 

Total    4  progenies 

57 

55 

51 

40 

53 

157 

2 

2867-69x4032-  1. 

2906-  1x2887-10. 

2907-  Ix         -22 

-  7x4032-41. 
4020-  7  X  2888-13 . 
4032-  2  X  2921-  4 . 

3x2888-  5. 

3x2922-16. 

4x2888-  1. 

4x2921-  4. 

5740 

5305 

5296,7052, 

7053... 

5301,5302 

5714 

5094 

5086 

5085 

5089 

5090-5092 

7 

7 

10 

16 

2 

8 

19 

14 

5 

25 

4 

5 

11 
16 
9 
6 
16 
10 
15 
13 

6 

2 

10 
16 
9 
IS 
21 
22 
12 
19 

3 

8 

11 
19 
4 
12 
12 
16 
17 
18 

4 
3 

9 
25 

4 
15 
18 

8 
18 
15 

10 
9 

26 
47 
18 
33 
46 
34 
45 
54 

Total,  10  progenies 

113 

105 

125 

120 

119 

322 

Total,  14  progenies 

170 

160 

176 

160 

172 

479 

Plant  Colors  in  Maize  123 

TABLE  4.     Fi  Progenies  of  Dilute  Sun  Red  IVa  x  Brown  V 


Pedigree  nos. 

Number  of  Fi  plants 

Group 

Pi 

Fi 

Purple 
la 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

2025-23x2192-14.. 
2029-  8  X 1945-11 . 

-  8x2013-19. 

-  8x2014-  8.. 
2031-10x1945-10. 

-32x2012-  1.. 
2948-16x4042-  2.. 
4253-  2x4299-  2.. 
4305-  5x4042-  2.. 

2333,  4314 

25 
30 
17 
5 
16 
20 
79 
46 
24 

2304,  3596 

2311 

2310,4034 

2309 

1 

2392 

5168,  A108,  A120.... 

5528,  6748A 

5193,  5194 

i 

Total,  9  progenies ...          .        .... 

262 

I 

2018-69x2192-18.. 
2030-13  X         -14.. 
2031-20x2012-  1.. 

2043-  2x2026-17.. 
2049-14x2192-14.. 
2473-  3x2341-  1. 
4370-  5  X  3000-  2 . 

2386,  4301 

30 

7 

55 

15 

24 

4 

8 

35 
6 

55 
18 
21 
2 
10 

4319 

2 

2325,      2326,      2543, 
2544,  2950,  2951 .  . 
2347,4326 

2336,  4327 

4029 

4746,  4747 

Total,  7  progenies 

143 

147 

2023-19x2192-12.. 

-23 X         -12.. 
2027-  9  X         -14. 
2410-  4x2417-  2. 

-  6x         -  1. 
5500-  5  X  5130-  1 . . 

2332,4311 

19 
15 
15 
9 
23 
24 

26 
16 
18 
6 
32 
25 

2330,  4310 

2334,  4316 

3 

2993,  2994 

2995-2998.    . 

A65 

Total,  6  progenies 

105 

123 

2025-10x2192-14.. 
2029-27x2012-  1.. 

-32  X         -  1 . . 

-34x2014-  8.. 

4315 

1 
4 
3 
1 

2 
3 
5 

1 

6 
5 
6 
2 

3 

2319,4055 

4 

2316,4318 

3 

2314,  4054 

6 

Total,  4  progenies 

- 

9 

11 

19 

17 

124 


R.  A.  Emerson 


TABLE  5.     Fo  Progenies  of  Dilute  Sun  Red  IVa  x  Brown  V 


Pedigree  no.3. 

Number  of  F2  plants 

Group 

Fi 

F2 

Purple 
la 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Brown 
V 

Green 
Via, 
b,  c 

1 

2310-  2.. 
2332-  1 . . 
2950-  1 . . 

-  4.. 
-17.. 
-19.. 

2995-  7 . . 

2996-  1 .  . 
4029-  2 .  . 
4034-  1 .  . 

-  2.. 

5193-  1 .  . 

5194-  5.. 
5528-  8.. 

4036,  4037 . 
2999,  3000 . 
5036,5037. 
5030,  5031 . 
5034,5035. 
5032,  5033 . 
5000-5007 
5008,  5009 . 

5095 

5098,5099. 

5104 

A135 

A136 

6748B 

15 
31 
36 
37 
32 
39 
75 
150 
61 
46 
42 
20 
10 
49 

7 

9 

12 

15 

5 

12 

24 

50 

23 

12 

20 

5 

3 

11 

6 
8 
12 
13 
14 
10 
20 
58 
11 
19 
17 
4 
12 
14 

3 

1 
2 
3 
6 
3 
5 
20 
5 
7 
8 
3 
1 
4 

3 
15 
10 

8 
13 
12 
21 
48 
22 
17 
13 

4 

4 
12 

7 

7 

9 

13 

9 

5 

17 

45 

11 

7 

21 

1 

7 

18 

Total,  14  progenies 

643 

208 

218 

71 

202 

177 

2 

2973-  5.. 

2974-  9.. 
4046-  3.. 
5173-  4.. 
S17-19... 

5056-5062. 
5063-5065. 
5157,5158. 

A128 

7762 

55 
75 
20 
19 
35 

23 
24 
11 
5 
11 

21 

23 
6 
8 
5 

6 

10 

5 

1 

1 

17 

18 

V 

9 

14 

17 

22 

4 

9 

4 

Total,  5  progenies   . . .  . 

204 

74 

63 

23 

65 

56 

Total,  19  progenies .... 

847 

282 

281 

94 

267 

233 

TABLE  6.     F2  Progenies    of  Dilute  Sun  Red  x  Brown  Backcrossed  with  Green 

(IVa  X  V)  X  Vic 


Pedigree  nos. 

Number  of  F2  plants 

Fi  X  Vic 

F2 

Purple 
la 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Brown 
V 

Green 
Via, 
b,  c 

2310-  1x2411-6.. 
2922-13x4029-  2.. 
4029-  2x2921-10.. 
4034-  1x2922-16.. 
-  2x2921-68.. 
5813-25x5528-  8.. 
A129-12xA108-6.. 

4035 

5652,5653.. 

5096 

5100-5103.. 

5105 

6749 

A243,A244. 

3 

22 
9 

10 

12 
3 

25 

4 
13 
18 
13 
5 
0 
19 

3 
19 
12 
17 
5 
2 
20 

6 
24 

8 
11 

4 

4 
15 

2 

27 

13 

9 

4 

1 

23 

17 
75 
51 
33 
16 
9 
48 

To  al,  7  progenies .  .  .  . 

84 

72 

78 

72 

79 

249 

Plant  Colors  in  Maize 


125 


TABLE  7.     Fj  Progenies  of  Purple  x  Green  and  Dilute  Sun  Red  x  Brown  Back- 
crossed  WITH  Dilute  Sun  Red 


(la  X  Vic)  X  IVa,  and  (IVa  x  V)  x 

IVa 

Pedigree  nos. 

Number  of  Fa  plants 

Group 

Fi  X  IVa 

F2 

Purple 
la 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

1 

2050-16  X  1992-13 

2889-54  X  4032-  1 

2414,  4069,  4070. .  . 
5741-5744 

18 
24 

16 

27 

21 
21 

15 
24 

Total,  2  progenies 

42 

43 

42 

39 

2 

6730  -  9  X  6748A-  5 . , 
6748A-16  X  6751   -22.. 

-18  X            -22.. 

-19  X            -  1 . . 

-20  X            -  1 . . 
A121-  Ox    A108-  8.. 

L188-  1  x5528  -  8.. 

7467,7828 

7229 

7230 

7231 

7232 

A241,  A242,  A401, 

A462 

6786,  S2 

87 
40 
28 
40 
30 

28 
4 

79 
32 

28 
33 
25 

25 
5 

75 
42 
26 
30 
32 

38 
3 

71 
41 
35 
36 
20 

45 
4 

Total,  7  progenies 

257 

227 

246 

252 

Total,  9  progenies 

299 

270 

288 

291 

TABLE  8. 


Fs  Progenies  of  Selfed  and  Back  crossed  Fo  Purple  Plants  of  the  Crosses 
Purple  la  x  Green  Vie  and  Dilute  Sun  Red  IVa  x  Brown  V 


Pedigree 

nos. 

Number  of  F3 

plants 

Group 

F2 

F3 

Purple 
la 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Brown 
V 

Green 

1513-41 

2015,  400S, 
1009 

204S,  2475, 
4010,4011 

4208 

4271 

4275 

5210 

5213 

5214 

32 

01 
15 
13 
10 

9 
25 
22 

14 

14 

7 
8 
8 
3 
7 
5 

8 

21 
5 
6 
6 
3 

(; 
5 

3 

7 
0 
1 
2 

0 

0 

1 

6 

18 
6 
3 
7 
1 
4 

12 

(VIa,b,c) 
8 

-68 

1 

2018-  2 

-  9 

10 
4 
3 

2020-  1 

3 

40O5-  6 

1 

-62 

-63 

1 
4 

Total,  8  progenies 

193 

66 

60 

16 

57 

34 

2020-117x2043-11 

4279 

4 

4 

11 

4 

4 

18 

126 


R,  A.  Emerson 

TABLE  8  (continued) 


Pedigree  nos. 

Number  of  F3  plants 

Group 

F2 

F3 

Purple 
la 

Sun  red 
lla 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Brown 
V 

1 
Green 

2 

1513  -  35 

-138 

2018  -    6 

4066  -    3 

6748B-  41 

2046 

2052 

4270 

5216,5217. 
7400 

11 
16 
25 
38 
12 

4 
6 
9 
14 
3 

6 
1 
5. 
13 
4 

1 
2 
5 
5 
0 

Total,  5  progenies 

102 

36 

29 

13 

1513-  59 

-  92 

-133 

4037-    5 

2047 

2053 

2049 

5136,5137. 

20 
24 
16 
35 

6 

6 

4 

15 

5 
3 
9 
6 

(Via) 
3 
3 
2 

7 

3 

Total,  4  progenies 

95 

31 

23 

15 

2020-46  X  2200-  8 
2411-  4x2412-  2 
2443-  2x         -  2 
2922-12x4037-  5 

4283 

2981-2983. 
2984-2986. 
5138-5140. 

5 

8 

7 

34 

1 

6 

8 

43 

3 

2 

7 

32 

3 
10 

4 
36 

Total,  4  progenies 

54 

58 

44 

53 

2018-27 

4280 

4276 

4277 

5079 

5010-5013. 

5218 

A78 

19 
19 
29 
11 
195 
29 
16 

5 
3 

7 
4 

77 

12 

6 

9 
9 
6 
4 
71 
6 
6 

(Vib) 
1 

2020-15 

-30 

3 

4 

4001-12 

1 

4 

4005-  5 

4066-  5 

5099-22 

29 
3 

1 

Total,  7  progenies 

318 

114 

111 

42 

(; 

1513-    2 

-110 

2018-  92 

-119 

2412-     1 

2050 

2051 

4273 

4269 

4033 

19 
16 
31 
33 
40 

3 
6 

13 
9 

13 

Total,  5  progenies . 

139 

44 

Plant  Colors  in  Maize 

TABLE  S  (concluded) 


127 


Pedigree  nos. 

Number  of  F3  plants 

Group 

F, 

Fa 

Purple 
la 

Suji  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Brown 
V 

Green 

5 
(con- 
tin- 
ued) 

2411-5x2412-1   . 
24^-1  X         -1   . 

4032 

4019,4020 

4 
8 

I 

S 

Tot^l,  2  progenies 

12 

9 

6 

4006-  I 

4065-14 

5014,5015. 
5209 

126 

42 

37 
12 

Total,  2  progenies 

168 

49 

TABLE  9.     F4  Progenies  of  Self-pollinated  Purple  Plants  of  F3  Lots  Consisting 
OF  Color  Types  la,  Ilia,  V.  and  VIb 


Pedigree  nos. 

Number  of  F4  plants 

Group 

F3 

F4 

Purple 
la 

Dilute 

purple 

Ilia 

Brown 

V    - 

Green 
VIb 

5010-  7 

-  9 

7020,  7021 

7022  7023 

51 
53 

46 
35 

15 
19 
17 
17 

12 
22 
26 
14 

8 
6 

1 

-11 

5011-  4 

7024,  7025 

5 

7028.  7029 

1 

Total,  4  progenies . 

185 

68 

74 

20 

4276-32 

5010-  2 

5011-  6 

5181,  A170 

46 
14 

28 

12 

2 

14 

2 

7092 

7091,6837 

Total,  3  progenies. 

8<S 

28 

3 

5011-2 

7026,  7027 

67 

21 

128 


R.  A.  Emerson 


TABLE  10.     F3  Progenies  of  F2  Sun  Red  Plants  of  the  Crosses  Purple  la  x  Green 
Vic  AND  Dilute  Sun  Red  IVa  x  Brown  V 


Pedigree  nos. 

Number  of  F3  plants 

Group 

F2 

F3 

Sun  red 
Ila 

Dilute 

sun  red 

IVa 

Green 

1513-152 

2038,2474,4292 

4286 

38 
19 
30 
9 
30 

11 

7 
12 

4 

8 

(Via,  c) 
11 

2018-    4 

*16 

-  39 

4287 

11 

-  44 

4288 

6 

-  56 

4289 

11 

1 

Total,  5  progenies 

126 

42 

55 

1513-100x1516-20.... 
2018-  56x2043-11.... 
2020-118  X         -11.... 

2039,  4293 

7 
3 
4 

8 
1 
9 

t23 

4290 

7 

4291 

20 

Total,  3  progenies 

14 

18 

50 

2 

4037-2 

5126,  5127 

23 

9 

3 

4037-24x2921-15 

5128,  5129,  7074 

50 

(Via) 
43 

*  Plus  one  brown  V  plant, 
t  Plus  one  purple  la  plant. 


Plant  Colors  in  Maize 


129 


TABLE  11.     F3  Progenies  of  F.  Dilute  Purple  Plants  of  the  Crosses  Purple  la 
X  Green  Vie  and  Dilute  Sun  Red  IVa  x  Brown  V 


Pedigree  nos. 

Number  of  F3  plants 

Group 

F2 

F3 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Green 

2018-18 

4037-  9 

5099-  7 

A120-13 

4296 

14 
38 
35 

8 

6 

9 

15 

1 

(VIb,  c) 
12 

5117,5118 

16 

A77 

19 

1 

A229 

3 

Total,  4  progenies 

95 

31 

50 

2922-16x4037-9 

5119-5121 

21 

25 

57 

2 

4066-9 

5219 

57 

21 

3 

4037-14 

5095-29 

5290-12 

5122,5123 

A63 

16 

9 

60 

(VIb) 
5 
1 

7056,7057 

14 

Total,  3  progenies 

85 

20 

4 

4065-50 1 

5212 

21 

TABLE  12.     F3  Progenies  of  Fi  Dilute  Sun  Red  Plants  of  the  Crosses  Purple  la  x 
Green  Vie  and  Dilute  Sun  Red  IVa  x  Brown  V 


Pedigree  nos. 

Number  of  F3  plants 

Group 

F, 

Fa 

Dilute 

sun  red 

IVa 

Green 
Vic 

4036-9 

6750-4 

A120-8 

5115 

16 
12 

6 

7247,  7399 

8 

1 

A228 

3 

Total,  3  progenies 

62 

17 

4036-8 

4042-2 

5116 

27 
65 

5166 

2 

Total,  2  progenies 

92 

2922-18x4042-2 

5169-5171 

69 

130 


R.  A.  Emerson 


TABLE  13.     F3  Progenies  of  F2  Brown  Plants  of  the  Crosses  Purple  la  x  Green  Vie 
AND  Dilute  Sun  Red  IVa  x  Brown  V 


Pedigree  nos. 

Number  of  F3  plants 

Group 

F2 

F3 

Brown 
V 

Green 

1513-12                    

2025,4313 

33 
16 
23 
16 

8 

(Via,  b,  c) 
35 

2020-  8                         

4309 

13 

-47                             

4305 

*n 

1 

-98          

4307 

8 

4065-12                           

5211 

7 

Total  5  progenies                        

96 

74 

1513-  16                           

2030 

21 
23 
30 
32 
94 
64 
29 
46 
15 

(Via,  b) 
6 

-  39       

2026 

10 

-143          

2027 

9 

-194                             

2023 

9 

2018-  69 

2539,2540,4299,4300 
2338,4302 

25 

-  96          

20 

2 

2020-  57                    

4306 

9 

4037-    6                             

5130,7076 

12 

6748B-37                                    .    . 

7401 

4 

Total,  9  progenies ...         

354 

104 

4037-6x2922-6 

5131-5133 

34 

41 

*  Plus  one  sun  red  Ila  plant. 


Plant  Colors  in  Maize 


131 


TABLE  14.  Progenies  of  F2  and  F3  Brown  Plants,  of  the  Crosses  Purple  la  x 
Green  Vie  and  Dilute  Sun  Red  IVa  x  Brown  V,  Crossed  with  Dilute  Sun  Red 
IVa  Plants 


Pedigree  nos. 

Number  of  F3  plants 

Group 

F.  X  IVa 

F3 

Purple 
la 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

1 

2018-69  X  2192-18. . 
4370-  5  X  3000-  2. . 

2386,  4301 

4746,4747 

30 

8 

35 
10 

Total,  2  progenies 

38 

45 

2410-4  X  2417-2. .  . . 
-6  X         -1. .  . . 

2993,  2994 

9 
23 

6 
32 

2995-2998 

2 

Total,  2  progenies 

32 

38 

3 

5095-20  X  L170-1  .  . 

S17 

15 

F3  X  IVa 

F4 

Number  of  F4  plants 

4 

2025-10  X  2192-14. . 

4315 

1 

2 

6 

3 

2030-13  X  2192-14. . 
20i3-  2  X  2026-17. . 

4319 

7 
15 

6 
18 

5 

2347,4326 

Total ,  2  progenies 

22 

24 

2023-19x2192-12.. 

-23  X          -12. . 

2027-  9  X         -14. . 

5500-  5  x5130-  1.. 

2332,  4311 

19 
15 
15 
24 

26 
16 
18 
25 

2330,4310 

2334,  4316 

6 

A65 

Total,  4  progenies. . . 

73 

85 

7 

2025-23  X  2192-14. . 
4253-  2  X  4299-  2. . 
4305-  5  X  4042-  2. . 

.2333,4314 

5528,  6748A 

.5193,5194 

25 

*46 

24 

Total,  3  progenies 

95 

*  Plus  one  dilute  sun  red  IVa  plant. 


132 


R.  A.  Emerson 


TABLE  15.     Fs  Progenies  of  Selfed  axd  Backcrossed  Green  Plants  of  the  Crosses 
Purple  la  x  Green  Vie  and  Dilute  Sun  Red  IVa  x  Brown  V 


Group 

Pedigree 

Xos. 

Number  of 
F3  plants 

F2 

F3 

(Green) 

1513   -  42  

2033     

(VI) 
22 

-106 

2036 

18 

-Ill 

2032 

13 

4036  -    6 

5114 

22 

4037  -  29 

4066  -    4 

5095  -  30 

674SB-  11 

5124,5125 

42 

1 

5215 

32 

A62 

8 

7402.                          .... 

22 

Total,  8  progenies 

179 

1514-  9           

2034     

20 

-37 

2035 

19 

-47 

2037 

18 

2 

6749-  1     

7242 

19 

-  4 

7243..               .    .    . 

20 

Total,  5  progenies 

96 

2019-  40 

2364,  4356 

(Via) 
*26 

-  63 

2356,  43^^ 

24 

-  92     

23S4 

10 

3 

-  98 

2374 

10 

-106 J 

2357 

15 

Total,  5  progenies 

85 

2019-33  

2^9,  43o4 

(Vlb) 
29 

—0/         

2373,  4353 

34 

4 

-73 

2379 

10 

-84 

2383 

14 

Total,  4  progenies 

87 

2019-17 

-25 

2395 

(Vic) 
14 

,. 

2^48,4357 

29 

Total,  2  progenies 

43 

*  Plus  one  brown  V  pUint. 


Plant  Colors  in  Maize 


133 


TABLE  16.     Fi  Progenies  of  Crosses  of  Green  Via,  VIb,  and  VTc  with  Dilute  Sun 

Red  IVa  5^ 


Pedigref 

'  nos. 

Number  of  Fi  plants 

Group 

Pi 

Fi 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

2047-25x2192-14 

2049-12  X         -14 

4300-14  X  4364-  1 

4307-  9x4042-  2 

2392 

16 
20 
52 
60 

2393 

1 

5198 

5183,5184 

Total,  4  progenies 

148 

2036-9  X  2192  14 

4725-2x5095-30 

4320 

9 
67 

A96,  A97 

2 

Total,  2  progenies 

76 

3 

2025-12x2192-14 

2335 

24 

2019-  29x1946-  4.... 

-  40x2192-18.... 
-63x         -18.... 

-  92x1945-10.... 
-98x         -10.... 
-104  X  2012-  1 . . . . 
-103x2192-18.... 

2398,  2399 

30 
5 
11 
13 
11 
13 
27 

19 

2365,  4340 

5 

2358,  4349 

10 

2385 

12 

4 

2375 

12 

2363 

12 

2359,  4351 

15 

Total,  7  Droeenies 

110 

85 

2019-33x2192-18 

-51  X194&-  4 

-57x2192-18 

-73x1945-11 

-84  X         -10 

2352,  4342 

5 

19 

8 

2 

22 

4 

2361,4347 

15 

5 

2369,2370,4345 

2377,  2378 

14 
6 

2382,4352 

26 

Total,  5  progenies 

56 

65 

2019-17x194^11 

-19  X         -11 

-25  X         -11 

2396,  2397 

43 

2381 

19 

2351,4344 

44 

6 

Total,  3  progenies 

106 

134 


R.  A.  Emerson 


TABLE  17.     F2  AND  Backcross  Progenies  of  Dilute  Sun  Red  IVa  x  Green  Vie 


Pedigree  nos. 

Number  of  Fo  plants 

Group 

Fi 

F2 

Dilute 

sun  red 

IVa 

Green 
Vic 

1983-34     

4502,  4503 

27 

199 

43 

11 

285-^  7         

4677-4679 

73 

1 

2866-  1                    

6471,  6472 

15 

Total,  3  progenies 

269 

99 

Fi  X  Vic 
2854-13  X  2887-69    

6325,  6326 

87 
42 
93 
90 
45 

96 

-16  X         -69 

2861-  Ix         -41 

2866-  2x2888-  2 

4707-82x4685-  1 

6319-6321 

45 

4686-4688 

100 

2 

5748-5750,  6485-6487 
6533-6535 

74 
43 

Total   5  progenies                              

357 

358 

TABLE 

18.     Fi  Progenies  of  Intercrosses 

BETWEEN  Green  Plants,  Via,  VIb,  and  Vie 

Pedigree  nos. 

Number  of  Fi  plants 

Group 

Pi 

Fi 

Brown 
V 

Green 
VI 

1 

2019-25x2019-106 

2354 

23 

2 

2019-25x2019-33 

2350,  4343 

22 

2019-  40  X  2019-  63                  

2367 

25 

-  98  x         -  40 

2376 

25 

3 

-104  X         -106            

2362 

22 

Total,  3  progenies 

72 

4 

2019-57x2019-51 

2371,4346 

24 

2019-  33x2019-63 

-  40  X          -33 

2355 

6 

8 
14 

7 
5 

19 

2366,  4341 

28 

5 

-  57  X          -98 

2372,  4350 

26 

-73x         -40 

-106  X          -51 

2380 

16 

2360 

16 

Total,  5  progenies 

40 

105 

Plant  Colors  in  Maize  135 

TABLE  19.     F2  Progenies  of  Crosses  Between  Brown  V  and  Green  Vie 


Pedigree 

nos. 

Number  of  F2  plants 

F, 

F2 

Brown 
V 

Green 
Via,  b,  c 

1514-12... 

2029 

19 
22 
25 
40 
15 
21 
46 
14 
53 
24 
38 

16 

-23. . . 

2031 

13 

-38 : 

2028 

16 

2983-  7... 

5071,  5072 

44 

-11... 

5070 

11 

2986-  4 

5078   

8 

-  9... 

5077 

36 

4035-35  .. 

5110 

6 

4068-  4... 

5225 

23 

-10 

5227 

20 

-11  . 



5226 

30 

Total, 

1 1  progenies 

317 

223 

TABLE  20.     F3  Progenies  from  F2  Brown  Plants  of  the  Cross  Brown  V  x  Green 

Vic 


Pedigree  nos. 

Number  of  F3  plants 

Group 

F2 

Fa 

Brown 
V 

Green 
VI 

2031-28 

4323 

19 
10 

-32 

2323 

1 

Total,  2  progenies                           

29 

2031-20 

2324,  2541,  2542, 

2948,  2949 

2327,  2328 

82 
18 

2 

-29 

34 
6 

Total,  2  progenies 

100 

40 

2029-27 

2320,  4321 

17 
22 

20 

-34 

2315,  4322 

19 

3 

Total,  2  progenies. ...                      

39 

39 

136 


R.  A.  Emerson 


TABLE  21. 


Fo  Progenies  of  the  Crosses  Sun  Red  Ila  x  Green  Vie  and  Dilute  Sun 
Red  IVa  x  Green  Via 


Pedigree  nos. 

Number  of  Fa  plants 

Group 

Fi 

Fj 

Sun  red 
Ila 

Dilute 

sun  red 

IVa 

Green 
Via,  c 

1514-32 

2040,  4294 

53 
40 
24 
26 
91 
203 
83 
47 
28 
20 
28 
49 
14 
35 
44 
42 

16 
14 
10 

4 
42 
55 
33 
13 

6 

2 
12 
21 

5 
16 

9 
10 

19 

-76 

2041,  4295 

23 

2083-  1  

4336,  4337 

11 

-  2  

4338,  4339 

11 

2981-  3          

4992,  4993 

45 

-  4 

4994-4996 

84 

4014r-  1 

5554-5557 

33 

-  3  

5559-5563 

13 

1 

4019-  2       

5691,  5692 

18 

-  4           

5685,  5686 

12 

4020-  1 

5708 

10 

4035-  3  

5111-5113 

24 

4040-  2       

5148,5149 

13 

6661-  9            

7379 

21 

6662-  1                    .    . 

7381 

29 

-  8 

7380 

17 

Total,  16  progenies 

827 

268 

383 

2398-  2 

4426,4427 

5097 

6951-6953 

28 
31 
127 
92 
65 

9 
18 
38 
25 
30 

12 

4029-  1 

4776-  1 

4780-  9 

-11 

21 
71 

2 

6960,  6961 

42 

6954-6956 

33 

Total,  5  progenies 

343 

120 

179 

1416-  1x1430-  1 

2888-22  x  4019-  2 

2922-18x4014-  3 

4014-  1x2922-  1 

4019-  2x2888-  1 

-  4x         -  1 

4020-  1 X  2887-69 

1494,  2074 

39 
16 
30 

3 
15 
24 

7 

39 
14 
26 
3 
14 
13 
14 

92 

5694B,  5695A 

5563-5565 

22 
68 

5558 

10 

3 

5697,5698 

22 

5689,  5690 

31 

5709 

22 

Total,  7  progenies 

134 

123 

267 

2921-15x4029-  1 

4774-  1x4710-45 

4781-  2  X  4707-35 

4782-  5  X         -18 

-13  X         -15 

4789-  4 X         -19 

6661-  9x6690-17 

6790-  5x6809-18 

5654-5656 

28 
78 
54 
103 
80 
50 
17 
32 

37 
71 
76 
88 
101 
43 
17 
32 

80 

6945,  6946 

151 

6967,  6968 

132 

6972,  6973 

195 

4 

6974-6978, 7667, 7668 
6989,  6990 

191 
108 

7328,  7329 

38 

7293 

67 

442 

465 

962 

Plant  Colors  in  Maize 


137 


TABLE  22.     Fo  Progenies  of  the  Crosses  Dilute  Purple  Ilia  x  Green  Vie  and 
Dilute  Sun  Red  IVa  x  Green  Vib 


Pedigree  nos. 

Number  of  Fn  plants 

Group 

Fi 

F2 

Dilute 

purple 

Illa 

Dilute 

sun  red 

IVa 

Green 
VIb,  c 

1514-61 

2019-10 

2072-  1 

-  9     

2044,  2560,  2561 .... 

2425,  2931,  2932 

4333,  43S4 

4335 

4899-4904 

5107 

5222 

44 
19 
38 
22 
153 
50 
46 
44 

14 

3 

12 

13 

58 
16 
18 
15 

16 

6 

10 

7 

1 

2956-  2 

4035-33 

73 

24 

4068-  6  

26 

-17 

5223 

11 

Total,  8  progenies .    . 

416 

149 

173 

2361-  1 

4070-  6 

4424,4425 

5235,  5236 

14 
133 
62 
30 
15 
30 

4 

51 

21 

11 

6 

9 

4 
52 

-11 

5237,5238 

6696,  6697 

A416,  A417 

A407,  A408 

19 

5269-  3 

15 

2 

A9&-14 

4 

A97-29 

13 

Total,  6  progenies 

274 

102 

107 

6790-1x6809-8 

7292 

26 

20 

56 

TABLE  23.     F2  Progenies  of  the  Cross  Sun  Red  Ila  x  Brown  V 


Pedigree 

nos. 

Number  of  F2  plants 

Fi 

F2 

Purple 
la 

Sun  red 
Ila 

Brown 
V 

Green 
Via 

5192-1 

A99 

14 
37 
69 

4 

5 

20 

5 

9 

23 

1 

-2 

-3 

7767 

7766,  S23 

2 

7 

Total,  3  progenies 

120 

29 

37 

10 

138  R-  A.  Emerson 

TABLE  24.    Fj  Progenies  of  the  Cross  Sun  Red  Ila  x  Dilute  Sun  Red  IVa 


roup 


Pedigree  nos. 


Number  of  F2  plants 


Fi 


413-  1. 

617-11. 
1520-  9. 
2065-  1. 
-  2. 
2414-  2. 
2975-  4. 
4028-  3. 
4040-  3. 
4332-26. 
4787-  4. 
5165-  2. 
7224-  4. 
7359-  1. 


1298 

1235 

2017 

4330 

2431,4331 

2987-2992 

4983-4986,7001,7002 

5643-5646 

5150,5151 

5491-5493 

6779-6782 

A114 

8118,8119 

8170,  8171 


7854-  1 8094,  8095 . 

A119-  4 i  A227 


Total,  16  progenies . 


Fi  X  IVa 

2065-  1  X     2043- 

2 

-  2x 

2 

4714-11  X    4774- 

1 

7224-  9  X     7225- 

7 

7354-  1  X     7315- 

5 

7770-  1  X     7768- 

172 

-  5x 

172 

A140-14X   A105- 

6 

L1773-15  X  L2049- 

11 

-20  X 

10 

L1844-14  X  L2048- 

24 

L2063-  5  X 

8 

-26  X  L2049- 

3 

L2064-  2  X  L2048- 

22 

4329 

2432,4332 

6943,  6944,  7676,  7677 

8115,8116 

8250,  8251 

8731 

8732 

A252,  A468 

8741 

8742 

8743 

8746 

8745 

8744 


Sun  red 
Ila 


Total,  14  progenies. 


40 
15 
31 
14 
48 
36 

373 
22 
41 
55 

166 
55 
43 
9 
35 
15 


998 


27 

6 

173 

196 

86 

16 

17 

92 

46 

41 

37 

56 

7 

11 


811 


Dilute 

sun  red 

IVa 


13 

4 

8 

5 

15 

9 

123 

7 

8 

16 

50 

20 

12 

3 

15 

6 


314 


30 

13 

133 

180 

96 

14 

11 

87 

37 

39 

41 

48 

7 

6 


742 


Plant  Colors  in  Maize 


139 


TABLE  25.     F3  Progenies  of  F2  Sun  Red  and  Dilute  Sun  Red  Plants  of  the  Cross 
Sun  Red  Ila  x  Dilute  Sun  Red  IVa 


Pedigree  nos. 

Number  of  F3  plants 

Group 

F2 

Fa 

Sun  red 
Ila 

Dilute 

sun  red 

IVa 

2990-  1 

5776-5778 

10 

4133-26 

5366 

40 

1 

Total,  2  progenies 

50 

2991-1 

-4 

5779,5780 

10 
9 

5781 

2 

Total,  2  progenies  

19 

7001-7x7002-11 

7684,7685 

101 

1235-  1 

1298-14 

2987-  2 

1633-1635,  2009..    .  . 

2011 

4997, 4998,  6999,  7000 
4999 

23 

•       14 

324 

12 

10 

2 

111 

3 

-  9 

4 

Total,  4  progenies 

373 

127 

TABLE  26.     F2  Progenies  of  the  Cross  Dilute  Purple  Illa  x  Dilute  Sun  Red  IVa 


Pedigree  nos. 

Number  of  F2  plants 

Group 

Fi 

F2 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

48.3-  3 

848-  2               

884 

16 
20 
47 
69 
65 
27 
17 

5 

1574 

10 

2425-  2 

4040-  1 

2946,2947 

5145-5147 

5240-5242 

52ai 

A226 

16 

26 

1 

4070-  8 

18 

-15 

8 

A119-  3 

4 

Total,  7  progenies 

261 

87 

F,  xIV 

7317-  6x  7322-  4 

AlOO-  6x  A140-31 

8204,  8205 

A249,  A467 

A250,     A251,     A465, 

A466 

8739 

18 
85 

83 
56 
33 

22 
95 

A140-12  X  A105-  3 

2 

L1760-  6xL2026-15 

L1838-16X           -15 

51 
63 

8738 

32 

Total,  5  progenies 

275 

263 

140  R.  A.  Emerson 

TABLE  27.    Fi  Progenies  of  the  Cross  Sun  Red  Ila  x  Dilute  Purple  Ilia 


Pedigree  nos. 

Number  of  Fi  plants 

Group 

Pi 

Fi 

Purple 
la 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

1529-18x1542-8 

6889-  1x6835-1 

2057 

10 
14 

7627       

1 

24 

2 

2903-2x2947-37 

^1796-4799     

74 

75 

488-  9x    730-  3 

1529-15x1549-35 

842,  1389 

18 
10 

23 

2058 

6 

3 

28 

29 

TABLE  28.     F2  Progenies  of  the  Cross  Sun  Red  Ila  x  Dilute  Purple  Ilia 


Pedigree  nos. 


Number  of  Fo  plants 


Fi  x  IVa 

F2 

Purple 
la 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

6650-  9  x  6691-    8 

7337 

8 

7 

9 

13 

8 

19 

35 

12 
7 
8 
10 
14 
22 
37 

13 
5 

6 
12 
14 
18 
36 

6 

6651-10  X         -     8 

73.38 

6 

7700-  4x7768-172 

-14 X         -172 

7769-  2  X         -172 

-  5x7315-  10 

-  7x         -    9 

8723,8724 

8725,8726 

8729,8730 

8263,8264 

8261,8262 

5 
15 
12 
15 
24 

Total,  7  progenies 

99 

110 

104 

83 

Plant  Colors  in  Maize 


141 


TABLE  29.     F2  Progenies  of  the  Cross  Purple  la  x  Dilute  Sun  Red  IV& 


Group 


Pedigree  nos. 


Fi 


478-  3. 

-  4. 
47^  1. 
484-24. 

-26. 
739-  1. 

849-  1. 

850-  3. 

851-  2. 

-  3. 

852-  1. 

-  2. 
1564-15. 
2971-  3. 
4028-  1. 

-  6. 

4045-  3. 

4046-  4. 
4070-  4. 

-12. 
5165-  8. 
5172-  3. 

5179-  1. 

-  6. 

5180-  5. 
S12-18. 


880 

881 

883 

907,  1531 

828,  1396,  1530. . 

1312,  1549 

1553,  1554 

1559 

1563 

1565 

1566,  1567 

1568 

4102 

4968-4976 

5647 

5082,  A66 

5154 

5159,5160 

5239 

5232,5233 

A117 

A126 

A130 

A131 

A133 

A208 


Number  of  F2  plants 


Purple 
la 


Total,  26  progenies. 


53 
49 
43 
39 
74 
97 
40 
10 
23 
16 
14 

2 
13 
65 
17 
138 
40 
65 
34 

7 
40 
17 
42 
12 
36 
27 


FixIVa 
740-  2  X    732-  1 
1105-  9  X 

-15  X 

-16  X 
1106-12  X 
1107-  4x 

-13  X 


849- 

852- 
848- 
851- 
850- 
2922-19  X  4046- 


4045-  3  X  2922-18 . 

4046-  4x4042-  2. 

4729-  8x5165-  8. 
5812-  3x5179-  6. 
6785-  1  X  6784-18. 
-  1  X  -26 . 
722C-  2  X  7268-  2. 
7263-  9x7240-10. 
A140-18xA106-4. 


1118,  1119 

1557,  1558 

1561,  1562 

1570,  1571 

1572,  1573 

1564 

1560 

5161,  5162,  A142 
A143 

5155,  5156 

5164,  5165,  A105- 

A107 

S12 

A132 

7429,  7430 

7431,  7432 

8111 

8008 

A248,  A469 


1,013 


Total,  17  progenies. 


39 
15 
11 
13 
9 
4 
10 

37 
23 

26 
7 
6 
10 
31 
33 
14 
35 


323 


Sun  red 
Ila 


18 

20 

15 

11 

25 

27 

10 

5 

5 

4 

5 

0 

2 

22 

5 

41 

10 

23 

10 

1 

14 

7 

15 

1 

11 

9 


Dilute 

purple 

Ilia 


316 


33 
14 
11 
10 
6 
6 


34 
17 

23 
2 
9 
14 
31 
30 
15 
44 


306 


12 

11 

12 

13 

23 

28 

14 

0 

3 

7 

3 

1 

1 

23 

5 

45 

13 

18 

9 

2 

13 

6 

11 

4 

10 

9 


296 


36 
14 

7 
12 
12 

8 
12 

39 
13 

27 
5 
3 

17 
36 
32 
18 
34 


325 


Dilute 

sun  red 

IVa 


4 
5 
3 
5 
10 
8 
2 
1 
0 
1 
1 
1 
0 
8 
0 
14 
5 
6 
3 
2 
5 
1 
7 
3 
3 
2 


100 


35 
15 

8 

11 

9 

4 

8 

30 

17 

26 

5 

5 

9 

26 

27 

14 

40 


289 


142 


R.  A.  Emerson 


TABLE  30.     F3  AND  r4  Progenies  of  F2  and  Equivalent  F3  Purple  Plants  of  the 
Cross  Purple  la  x  Dilute  Sun  Red  IVa 


Pedigree  nos. 

Number  of  F3  plants 

Group 

F2 

F3 

Purple 
la 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

271-  9     

496,  497,722 

1535,  1577 

1536,  2002 

5177 

6742,  A68 

6743,  A69 

A147 

34 
35 
42 
25 
48 
74 
10 

11 
13 
14 

8 
24 
32 

3 

9 

9 
10 

8 
18 
22 

2 

5 

1312-52       

1 

-59       

2 

4102-  2 

3 

5082-23  

8 

1 

-33     

9 

5159-  3              

0 

268 

105 

78 

28 

1312-59  X  1140-18.... 

1575,    1576,    2000, 
2001 

26 

25 

24 

21 

271-  5              

489,  490 

12 
34 
14 

5 

16 

1 

1312-87 

1537 

A149  : 

5160-  8 

60 

22 

2 

148-  Ix    271-  5.... 
1312-87  X  1140-18.... 
4102-13x4042-  2.... 

478,  479 

12 

9 

11 

6 
13 
12 

1578 

5179,  5180,  Al  13. 

32 

31 

271-  3                 .         1  492.  493 

49 
44 
43 
26 

10 

18 

11 

9 

1312-50         

1534 

- 

-81           

1581 

4102-12               

5178 

3 

Total  4  progenies      

162 

48 

271-12  X      80-8 

483,  484 

17 

15 

F3 

F4 

Number  of  F4  plants 

4 

722-  5  X    720-  1 . . . . 
A68-31 

739,762,856,1550. 
A339  

41 
13 

54 
5 

722-3  X    719-3 

-3x    721-7 

740,  761,  849,  850. 

848 

40 
12 

44 

8 

5 

Total,  2  progenies                    

52 

52 

6 

722-1 

724-1  x    722-1 

760,905,1121,1526 

857 

69 
18 

Plant  Colors  in  Maize 


143 


TABLE  31.  Fa  Progenies  of  Sun  Red,  Dilute  Purple,  and  Dilute  Sun  Red  F2  Plants 
OF  THE  Cross  Purple  la  x  Dilute  Sun  Red  IVa 


Pedigree  nos. 

Number  of  F3  plants 

Group 

F2 

Fa 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

1312-  4 

1579 

17 

18 
18 

-36 

1542  

-55 

1543         

53 

1 

1312-38 

5159-  8      

1580,2010 

A148 

24 
14 
16 
16 

7 
5 

A 13'^-  3 

A233     

7 

A133-12 

A193 

5 

70 

24 

80-4 

271-  4 

487  488                .    . 

30 
50 
17 

494         

A117-12 

A473            

97 

271-  1 

-  7               

491     

55 
42 
46 
36 
11 
27 

25 

2 

495 

16 

1312-  3 

1538 

16 

-65 

1539,  1999 

12 

5234-  1 

-  8                   

A86      

5 

A87 

12 

Total  6  progenies                  

217 

86 

80-  8 

485,  486 

19 

1312-11 

1544,  1872 

27 

3 

A133-  3 

A192 



26 

72 

144  R.  A.  Emerson 

TABLE  32.    Fj  Progenies  of  the  Cross  Weak  Sun  Red  lib  x  Dilute  Sun  Red  IVa 


Pedigree  nos. 

Number  of  F2  plants 

Fi 

F2 

Weak 

sun  red 

lib 

Dilute 

sun  red 

IVa 

2187-21       

4135,5371 

4133,  5365 

151 

160 

112 

122 

99 

176 

141 

17 

35 

89 

17 

181 

41 

-23       

59 

2189-16 

4138,5377 

5373 

4142,  5374 

4143,  5376 

2391,4144,  5375,7072.  .. 
5715 

25 

2190-  4  

44 

-  4  X  2187-  1 

42 

-  7  X         -23 

75 

-  7       

49 

4022-  5                  

7 

4134-22                           

5370 

14 

-56       

5378 

5411 

A58 

27 

4162-41                  

3 

5364-  6 

43 

Total,  12  progenies 

1,300 

429 

TABLE  33.     F3  Progenies  of  the  Cross  Weak  Sun  Red  lib  x  Dilute  Sun  Red  IVa 


Pedigree  nos. 

Number  of  F3  plants 

Group 

F2 

F3 

Weak 

sun  red 

lib 

Dilute 

sun  red 

IVa 

1 

4136-43                             

5384,6805,7740 

77 

4136-11         

5383,  6802 

86 
22 
13 

7 

39 

4138-15              

5385 

8 

2 

5365-26 

5371-23 

A61  

5 

6798 

2 

128 

54 

3 

4143-23 

5392,  5393 

95 

Plant  Colors  in  Maize 


145 


TABLE  34.  F2  Progenies  of  the  Crosses  Weak  Purple  lb  x  Dilute  Purple  Ilia, 
Weak  Purple  lb  x  Dilute  Sun  Red  IVa,  and  Weak  Sun  Red  lib  x  Dilute  Purple 
Ilia 


Pedigree  nos. 

N 

limber  of  F2  plants 

Group 

Fi  X  Ilia,  IVa 

F2 

Weak 

purple 

lb 

Weak 

sun  red 

lib 

Dilute 
purple 
Ilia 

Dilute 

sun  red 

IVa 

A208-15  X  A445-  1. 

A452-  4x  7302-  4, 

-18  X          -44. 

A822 

4 
53 

84 

4 

57 
102 

1 

A789,  A790 

A791,  A792 

Total,  3  progenies 

141 

163 

7507-  2x  A43S-  5.. 
A292-17  X  A441-  6. . 
A441-  2x  7515-  3.. 

-  6x          -  8.. 

-  7x          -  8.. 
-12x  A339-10.. 
-18  x  7515-  4.. 

A793-A796 

A788 

77 
55 
76 
64 
68 
64 
77 

86 
58 
80 
68 
60 
70 
104 

61 
49 
69 
69 
66 
69 
77 

56 

38 

108 

88 

A783 

A784 

2 

A785 

53 

103 

91 

A786 

A787 

Total,  7  progenies 

481 

526 

460 

'i'^7 

3 

S27-2  x  6805-9 j  7773,  7774. ....... 

21 

28 

22 

27 

TABLE  35.    F2  Progenies  of  the  Cross  Green  IVg  x  Brown  V 


Pedigree  nos. 

Number  of  F2  plants 

Fi 

F2 

Purple 
la,  g 

Sun  red 
Ila,  g 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Brown 
V 

Green 

Illg. 

IVg,  VI 

2400-  1 

2952-  1 

-11 

-24 

-32 

2958-2961 .  .  . 
4844-4860 .  .  , 
4861-4871 .  .  . 

4872-4884 .  .  . 
4885-4898 .  .  . 
4822-4829 .  . . 

19 
59 
43 
42 
62 
84 

5 
21 
15 
12 
23 
24 

6 
8 
7 
9 
12 
25 

1 
1 
4 
2 
3 
8 

5 
14 
11 
15 
20 
23 

2 
18 
15 
16 
17 

2953-10 

30 

Total,  6  progenies 

309 

100 

67 

19 

88 

98 

146  R.  A.  Emerson 

TABLE  36.    Fj  Progenies  of  the  Cross  Green  IVg  x  Brown  V 


Number  of  Fj  plants 

Pedigree  nos. 

Purple 

Sun  red 

Dilute 
purple 

Dilute 
sun  red 

Brown 

Green 

Fi 

Purple 

anthers 

la 

Green 

anthers 

Ig 

? 
an- 
thers 
I 

Pink 

anthers 

Ila 

Green 

anthers 

Ilg 

7 
an- 
thers 
11 

Purple 

anthers 

Ilia 

Pink 

anthers 
IVa 

Green 

anthers 

V 

Green 
anthers 

Illg, 
IVg,  VI 

2958-2961 

4822-4829 

4844-4860 

14 
61 
42 

5 
12 
16 

0 

11 

1 

1 
10 
10 

1 

4 
7 

3 
10 
4 

6 
25 

8 

1 

8 

1 

5 
23 

14 

2 
30 
IS 

Total,  3  progenies . 

117 

33 

12 

21 

12 

17 

39 

10 

42 

50 

TABLE  37.     F^ 

Progenies 

OF   THE 

Cross  Purple  Ig  x  Green  Vie 

Pedigree  nos. 

Number  of  F2  plants 

Group 

F. 

F, 

Purple 

Sun  red 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Brown 
V 

Green 

5534-39 

6795,  6796.. 
7376 

(la.  g) 

65 
15 

(Ila.  g) 

11 
2 

6 
3 

7 
2 

15 
-     5 

(Illg, 
IVg,  VI) 
26 

1 

6655-  6 

1 

80 

13 

9 

9 

20 

27 

2 

F,  X  Vic 

6655-  6x6690-17.. 
6808-13x6790-  8.. 

7349 

7290 

(la) 

6 

30 

(Ila) 
13 
16 

13 
18 

15 
16 

17 
14 

(VI) 
46 
49 

36 

29 

31 

31 

31 

95 

Fi  X  IVa 
6779-2x6790-8..  .. 

6792-2 X          -8 

-8x          -8.... 

7299,7300.. 

7297 

7296 

27 
29 
59 

25 
29 
43 

30 

19 
46 

31 
32 

48 

3 

Total,  3  progenies 

115 

97 

95 

111 

4 

Fi  X  IVg 
6656-9x6652-6 

7344 

(la,  Ig) 
23 

(Ila,  Ilg) 
15 

10 

15 

(Illg,  IVg) 
13 

Plant  Colors  in  Maize 


147 


TABLE  38.     F2  Progeniks  of  the  Crosses  Purple  Ig  x  Dilute  Sun  Red  IVa  and  Purple 

la  X  Green  IVg 


Pedigree  nos. 

Number  of  F2  plants 

Group 

Fi 

F2 

Purple 
la,  g 

Sun  red 
Ila,  g 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Green 
Illg,  IVg 

1 

2954-3.. 

2956-3.. 

-4.. 

5042-5045 . 
4905-4914. 
4915-4929. 

43 
144 

56 

14 
42 
15 

13 
25 
21 

5 

14 

3 

7 
7 
6 

Total,  3  progenies. .  .  . 

243 

71 

59 

22 

20 

2 

2421-1 . . 

-2.. 

2910,2911. 
2908,  2909. 

14 

26 

7 
13 

5 
4 

1 
1 

1 
0 

Total,  2  progenies. . .  . 

40 

20 

9 

2 

1 

TABLE  39.     F3  and  F4  Progenies  from  Fo  and  Equivalent  F3  Purples  of  the  Cross 

Purple  la  x  Green  IVg 


Pedigree  nos. 

Number  of  F3  and  F4  plants 

Group 

F2  and  F3 

F3  and  F4 

Purple 

Sun  red 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Green 

2909-16 

5251,  5252 

(la,  g) 
9 

(Ila,  g) 
4 

3 

0 

0 

1 

F2  X  IVg 
2909-4  X  2884-21 

5255 

15 

15 

5 

1 

(II Ig,  IVg) 
9 

F2  X  VIc 

2909-4  X  2887-38 

.5^56.  A  94 

(la) 
27 

(Ila) 
19 

15 

14 

2 

5251-6 1  6708 

31 

7 

2909-9 

5257,  5258 
6652 

(Ig) 
14 
23 

(Ilg) 
2 

9 

5 

3 

5252-1 

9 

Total,  2  progenies 

37 

11 

14 

148 


R.  A.  Emerson 

TABLE  39  (concluded) 


Pedigree  nos. 

Number 

of  F3  and  F4  plants 

Group 

Fa  and  Fj 

F3  and  F4 

Purple 

Sun  red 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Green 

3 

(coiv- 
tin- 

Fa,  F3  X  IVg 
2909-  9  X  2884r-21 

4717-71  X  5252-  1 
5252-  1  X  5669-  3 

5259,  5260, 
7007,  7008, 
7060,  7061. 

6654A 

6654B 

(Ig) 

19 

11 

4 

(Ilg) 

IS 
8 
6 

(Illg,  IVg) 

34 

13 

6 

Total,  3  progenies       

34 

32 

53 

ued) 

F2,  F3  X  Vic 
2909-  9  X  2887-38 
4057-  1  X  2909-  9 
5251-  1  X  5813-18 
5813-18  X  5251-  1 

5261,5262. 
5534,  6790. 

6655 

6656 

(la) 

14 

-     16 

9 

5 

(Ila) 
11 
10 
16 
11 

7 

13 

7 

6 

11 

18 

14 

9 

Total,  4  progenies 

44 

48 

33 

52 

2909-34 

5253,  5254, 

7090 

6658,7015. 

(Ig) 

26 
30 

(Illg) 

5251-  7 

6 
12 

4 

Total,  2  progenies 

56 

18 

Fa  X  IVg 
4717-20  X  .5251-7. . 

6659,  7014. 

28 

27 

Plant  Colors  in  Maize 


149 


TABLE  40.     F3  AND  Equivalent  F4  Progenies  from  F2  and  F3  Sun  Reds  and  Dilute 
Purples  of  the  Cross  Purple  la  x  Green  IVg 


Pedigree  nos. 

Number  of  F3  and  F4  plants 

Group 

F2  and  F3 

F3  and  F4 

Sun  red 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

2090-20 

5278 

(Ila) 

.   30 

37 

30 

8 

5251-  8       

6648 

10 

1 

-10                    

6709 

8 

Total,  3  progenies 

97 

26 

2909-  8     

5270-5273 

5280-5283 

5274-5277 

(Ila,  g) 

43 

64 

121 

-26 

-32 

Total  3  progenies  . .        

228 

2 

F2  X  IVg 
2909-26  X  28M-35 

Fo  X  Vic 
2909-26x2887-38 

5284-5287,7137. 

5288,  5289 

41 

(Ila) 
67 

Total,  2  progenies. . .            .... 

108 

2909-21 

5265,5266 

46 

9 

3 

F2  X  IVg 
2909-21  X  2884-35 

5267,5268 

5269 



44 
41 

31 

F2  X  Vic 
2887-31  X  2909-21 

51 

Total,  2  progenies 

85 

82 

150 


R.  A.  Emerson 


TABLE  41.    F2  Progenies  of  the  Cross  Purple  Ig  x  Green  IVg 


Pedigree  nos. 

Number  of  F2  plants 

Group 

Fi 

F2 

Purple 

Sun  red 

Dilute 
purple 
Ilia 

Dilute 

sun  red 

IVa 

Green 
Illg,  IVg 

5255  -  6 

7094,  7095, 

7701,7702 

7010,7011. 

7375 

7365 

7366 

7368,  8491 . 

7378 

7377 

(Ig) 
80 
54 
23 
28 
11 
43 
21 
33 

dig) 
24 
22 

7 
12 

3 
17 

7 
13 

5259   -  3 

55 
25 

6654B-  3 

9 

6659  -15 

12 

1 

-22 

5 

-27 

24 

6660  -  9 

10 

-12 

10 

Total,  8  progenies 

293 

105 

150 

Fi  X  IVa 
6659-19  X  6691-8.. 
6660-  3  X         -8. . 

Fi  X  Vic 
6654A-2  X  6690-9 

B-1 X          -17 

7339 

7340 

7335 

7336 

(  la) 

14 

9 

20 
15 

(Ila) 

9 

11 

15 

26 

14 

12 

13 
23 

12 
11 

10 
37 

2 

Total,  4  progenies . 

58 

61 

62 

70 

TABLE  42.     F2  Progenies  of  - 

rHE  Cross  Dilute  Purple  Ilia  x  Green  IVg 

Pedigree  nos. 

Number  of  Fo  plants 

Group 

Fi 

F2 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Green 
Illg,  IVg 

1 

2403-1 

2962-2966 

23 

8 

10 

2420-  1 

2904,  2905 

5038-5041 

6826,  6827 

6828,  6829 

6669,  6670 

6675-6678 

6679-6682 

17 
63 
36 
78 
31 
41 
62 

5 
26 

8 
32 
16 
14 
12 

9 

2954-  4 

34 

2967-  2 

17 

-11 

31 

2 

5263-  4 

8 

5267-  5 

27 

-12 

22 

Total,  7  progenies 

328 

113 

148 

3 

Fi  X  IVg 
7322-3x7317-4 

8210-8213 

46 

45 

86 

Plant  Colors  in  Maize 


151 


TABLE  43.     F3  and  F4  Progenies  from  Fa  and  Equivalent  F3  Dilute  Purples,  Dilute 
Sun  Reds,  and  Greens,  of  the  Cross  Dilute  Purple  Ilia  x  Green  IVg 


Pedigree  nos. 


F2  and  F3 


2966-  7. 
5049-25. 
5050-  6. 


F3  and  F4 


5049-5055 

6.S16-6818,  7441 

6822-6824,  7058,7059. 


Total,  3  progenies. 


6676-12 1  7383 

6828-12 7658-7660. 


Total,  2  progenies. 


Number  of  F3  and  F4  plants 


Dilute 

purple 

Illa 


50 
52 
41 


143 


26 
14 


40 


Dilute 

sun  red 

IVa 


Green 


48 


14 


(Hlg,  IVg) 
26 
20 
27 


73 


16 

7 


23 


5052-7. 
6676-8. 


6825,  7323,  7442. 
7382,  A266 


Total,  2  progenies. 


5049-37 6819-6821. 


2905-22. 
5053-  1. 


2547-2550 

6875,  6911,  6912. 


Total,  2  progenies . 


5050-  1. 

5054-10. 

5055-  2. 

-  5. 


6874 

6745,  6872,  6873. 

6871,7315 

7515 


Total,  4  progenies . 


27 
55 


82 


23 


62 


(Illg) 
16 


21 
42 


(IVg) 

9 

13 


63 


22 


17 

108 

51 

21 


197 


290.>-  5 

-19 

5049- 

-13 

5052- 

-3 

-  0 

-12 

6829-  9 1 

5243,  5244 . 
5245,  5246 . 
6913,  6914. 
6833 

S5 

6832 

7655-7657. 


Total,  7  progenies. 


(Illg,  IVg) 
5 
13 
11 
24 
15 
32 
30 


130 


152 


R.  A.  Emerson 


TABLE  44.     F2  Progenies  of  the  Crosses  Sun  Red  Ilg  x  Green  IVg,  Sun  Red  Ila 
X  Green  IVg,  and  Dilute  Sun  Red  IVa  x  Green  IVg 


Pedigree 

nos. 

Number  of  F2  plants 

Group 

Fi 

F2 

Sun 

red 

Dilute 
sun  red 

Green 

Pink 

anthers 

Ila 

Green 

anthers 

Ilg 

Pink 

anthers 

IVa 

Green 

anthers 

IVg 

1 

4787-6 

52&4-3 

6983,6984 

7003-7006 

122 
94 

52 
25 

Total,  2  progenies .... 

216 

77 

2 

Fi  X  IVg 

7317-6  X  7318-4 

7318-1  X  7317-4 

-4x         -6 

8214-8217 

.8222-8225 

8218-8221 

22 
38 
45 

31 
25 
34 

24 
34 
47 

32 
26 
51 

Total,  3  progenies 

105 

90 

105 

109 

5267-3 

6671-6674 

.7725,7726 

55 
30 

22 

3 

F,  X  IVg 
7031-14x6857-5... 

30 

Plant  Colors  in  Maize 


153 


TABLE  45.     Fi  Progeotes  of  Crosses  of  Sun  Red  Ila  and  Dilute  Sun  Red  IVa  with 

Green  Illg  and  IVg 


Pedigree 

nos. 

Number  of  Fi  plants 

Group 

Pi 

Fi 

Purple 
la 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Green 

Ila  X  Illg 
7097-5  X  A 159-25.  .. 
7357-3  X  7356-  1 .  . . 

7710 

33 
31 

8151,8152 

1 

Total,  2  progenies 

&4 

IVa  X  Illg 

A9-22X  7097-1 

7709 

4 

IVa  X  IVg 
6860-  8x6869-1.... 
A9-14X  7060-1..  .. 

7713 

28 
31 

7708,  A283,  A284 

Total,  2  progenies 

59 

IVa  X  Illg 

6860-13x6871-39... 
6861-  2  X  6751-  3. .  . 

7714 

11 
9 

12 

18 

2 

7711 

Total,  2  progenies 

20 

30 

IVa  X  Illg 

6861-4  X  6882-5 

7039-3x7061-1 

7512,  7513,  7716. 

7727,7728 

25 
44 

11 
43 

(Illg,  IVg) 
34 
72 

Total,  2  progenies 

69 

54 

106 

IVa  X  Illg 

7312-8x7313-2 

7313-2  x  7314-1 

7314-1  X  7313-1 

-6x         -2 

8183 

86 

31 

126 

85 

(Illg) 
92 

8184 

19 

3 

8200,  8201 

8185 

129 
98 

Total,  4  progenies 

328 

338 

154 


R,  A.  Emerson 


TABLE  46.     F2  Phogeniks  of  the  Cross  Green  IVg  x  Green  Vie 


Pedigree  nos. 

Number  of  F2  plants 

Group 

Fi 

F2 

Dilute 

sun  red 

IVa 

Green 

5534-4                       

6791,  6792 

7179,7180 

7181,  7182 

7177,  7178 

7175,7176 

7163,7164 

7169,  7170 

7171,7172 

35 
51 
32 
64 
63 
52 
60 
63 

(IVg,   Vic) 
29 

6530-1         

43 

-2         

30 

6531-1              

42 

1 

-2                  

38 

7032-1       

39 

7036-3              

36 

7037-2       

34 

420 

291 

Fi  X  Vic 
7032-7  X  6878-42  

7729,7730 

7767,7768 

24 
42 

iVIc) 
24 

7034-5  X         -42  .             

34 

66 

58 

2 

Fi  X  IVg 
7037-4  X  7049-7              

7173,  7174 

7731,7732 

48 
48 

(IVg) 
50 

7049-1x7037-4 

46 

Total   2  progenies                   

96 

96 

TABLE  47.     F3  Progenies  of  F2  Dilute  Sun  I 

Green  Vie 

Ied  Plants  of  th 

E  Cross  Green  xVg  x 

Pedigree  nos. 

Number  of  F3  plants 

Group 

F2 

F3 

Dilute 

sun  red 

IVa 

Green 
IVg,  Vic 

6791-  3     

7148,7149 

7154,7155 

7159 

23 
69 
16 

19 

6792-  6     

45 

1 

-11             

13 

Total,  3  progenies 

108 

77 

6791-22 

7150,  7151 

7152,7153 

7157 

7158 

7160 

65 
49 
38 
23 
12 

23 

-23     

18 

6792-  7         

12 

2 

-10 

10 

-13         

3 

Total,  5  progenies 

187 

66 

6792-  5 

-25     

7156 

7161 

48 
30 

3 

Total,  2  progenies 

78 

Plant  Colors  in  Maize  155 

TABLE  48.     Fa  and  F3  Progenies  of  the  Cross  Green  IVg  x  Green  Via 


Pedigree  nos. 

Number  of  Fa  and  F3  plants 

Group 

Fi 

Fa 

Sun  red 

Dilute 

sun  red 

IVa 

Green 

2400-  2 

2952-  5 

-22 

2902,2903 

4838-4843 

4830-4837 

4810-4813 

4814-4817 

4818-4821 

4930,  4931 

(Ila,  g) 

7 

36 

99 

88 

111 

92 

153 

3 
3 
15 
32 
20 
30 
58 

(IVg,VIa,c) 

5 

18 

57 

1 

2953-  4 

-  7 

-21 

2957-  2 

59 

62 

45 

102 

Total,  7  progenies 

586 

161 

348 

2 

Fa 
4930-31 

F3 
6991,6992 

119 

2903-  2 

4930-22 

4783-4786 

6993,  6994 

(Ila) 

99 

130 

(Via) 
32 
39 

3 

Total,  2  progenies 

229 

71 

Fa  X  IVa 
2903-2x2889-38 

4787-4790 

55 

156 


R.  A.  Emerson 


TABLE  49.     F2  Progenies  of  the  Cross  Green  Illg  x  Green  Vie,  and  Fi  Progenies  of 
Crosses  of  F2  Greens  with  Sun  Red  Ila  and  Dilute  Sun  Red  IVa 


Pedigree  nos. 

Number  of  F2  plants 

Group 

Fi 

F2 

Purple 
la 

Sun  red 
Ila 

Dilute 

purple 

Ilia 

Dilute 

sun  red 

IVa 

Green 

Illg,  IVg, 

VIb,  c 

2907-8  

5297,5298.. 

7085,    7086, 

7722,  7723 

28 
81 

11 
26 

38 

5262-5 

1 

97 

Total   2  Droeenies 

lotai,^  progenies 

109 

37 

135 

Pi 

Fi 

Number  of  Fi  plants 

Illg  X  Ila 
7085-10  XA159-24. 

7717 

27 

2 

Illg  X  IVa 
7086-2  X  7102-7. .  . . 
-3  X         -8. .  .  . 

7207 

7719     . 

14 
25 

Total,  2  progenies .   . 

39 

3 

Illg  X  Ila 

708&-6X  A159-17.. 

Illg  X  IVa 
708&-4  X  7102-8. . . . 

7718,   A298, 
A299 

7720 

28 

41 

11 

9 

4 

IVg  X  IVa 

7086-8  X  7102-8. .  . . 

7721 

22 

Mkmoik  39 


Plate  I 


ANTHER,  GLUME,  AND  RACIIIS  COLOR  OF  PURPLE 

1,  Purple,   type   la,   typical,   anthers   purple:   2,   type  la   with    »■'"'',  anthers   near- 
black  ;  3,  type  la  with  i>r,  anthers  reddish  ;  4,  type  Ij;.  with  Jiy  or  r'J,  anthers  yreen 
U'rawings   by   C.    \V.    Kedwood,   somewhat   diagrammatic) 


Mkmoir  39 


Plate  II 


CW.f^a.dv-/-ood 


AXTHER,    OLT-ME,    AXD    RACHIS    COLOR    OF    T^ILFTE    PT'RPLE     .\XT>    OREEX 

4.  Groon,   typos  Ilii:  a.ul   IVf:  with   R<J  or   rr/.   ^n-oon   (hruout 

(Drawings   by   C.    W.    Redwood,   somewhat   diajjramniatie) 


ilEMOIR    39 


Plate  III 


I 


ANTHER,   GLUME,   AXD   KACIIIS   COLOR   OF   SIX   REP   AXP   DILUTE    SUX   RED 

1.  Snn    red,    type    Ila.    intonsoly    pi.smenterl   form 

2.  Dilutf  sun  rorl.  tyi.p  IVa.  intensely  pipniontc.l  f,,rm  :  .".  an.l  4.  near-sreen 
forms,  little  col., r  in  ^lnnl.■s.  nntli.-rs  preen  witli  reddish  stipplins  as  shown  in 
enlarged   anther 

fr)rawings   by    C.    W.    Redwood,    somewhat    diagrammatic) 


Mkmoih  n9 


Plaie  IV 


\ 


AXTIIER,   GLUME,  AXD  RACHIS   COLOR   OF   BROWX   AXD   GREEX 

1.   Brown,     type     ^'.     intensely    pipmented,    homozygous    form  :     2.     typo    V.     less 
intensely  pigmented   form,  heterozygous   for  B   or  PI  or  both 

3,   Green,   type  Vic  :   4.   type   VIb,   green   with    tinge   of  brown   due   to  PI   and   r''' 
(Drawings   by   C.    W.   Redwood,   somewhat   diagrammatic) 


Mkmuiu  39 


Platk  V 


CULM,    IirSK,    AND    SHEATH    COLOR    OF    PIRPLE    AXD    SUX    RED 
1,   Purplo,  tj-pe  la;  2,  weak  purple,  type  II) 

3,   Sun   red.    t.vpe   lla  ;   4,    weak    sun  "red.    iy]n-    Ilh;    r,,    t.vi»^    Ilh.    inner   luisks   of 
lower  ear  hiphly  colored  from  exposure  to  sunlipht  directly  after  beinj;  torn  apart 
(Drawings  1  and  3  by  C.  W.  Redwood;  2.  4,  and  5  by  Bernico  M.   Branson) 


Memoir  39 


Plate  VI 


CW-Kcdwood 


CL'LM,     inSK.     AND     SHKATIT     COLOR     OF     DILUTK     PfRPLE.     -nTIXTTE     SUX     RED, 

liKOWX,   A.ND   GREEN 

1.  Diluti'  purpip  anrl  dilute  sun  red,  types  Ilia  and  IVa  ;  2,  more  hishlv  colored 
fonri  of  tjiies  Ilia  and  IVa 

'■'..   I'.iown.   type   V 

4.  (Ir.-on,  types  VIb  and  VI<- :  n.  type  Via.  with  some  brown  in  outer  husks 
due  to  li 

(Drawings  by  C.   \V.  Kedwood) 


Mkmoik  3!) 


Plaik  VII 


\ 
2      ^iJ/ 


'W 


iLVTURE    CULM,    HUSK,    AXD    COB    COLOR 
1.   Purplo.   typo  Ta ;   2,   sun    red.   type   Ila  :   3.   dilute  purple,   type   Tlla  :   4.    more 
intensely    pigmented    form    of    type    llla:    .".    l)ro\vn.    type    V:    C,    dilute    sun    red. 


type   IVa 


(Drawiugs  by   Carrie  M.   Preston) 


Mkmoiu  39 


Plate  VIII 


DEVELOPMENT    OF    COLOR    IX    DARKNESS 
Tasspls    ami    slionths    di'veloped    iinrter    Ijlack    paper    liaes  :    1.    purjilc.    type    la  • 
2,  brown,   type  V:   3,   dilute  purple,   type  Ilia:   4,  sun   red,    type  Ila,   no   red   color 
(Drawings  by  Carrie  M.  Preston) 


H      U 


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p-      — 

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Memoir  39 


Plate  X 


COLOR  DEVELOPMEXT  IX  BROKEN  LEAVES 

1.  nihitp  sun  red.  type  IVa.  about  one  week  after  the  leaf  was  creased- 
2.  dilute  purple,  type  Ilia  with  japc.nica  white  stripe.s,  about  three  days  after  the 
leaf  was  creased 

(Drawings  by  Carrie  M.   I'reston) 


ilKMOIH    :i9 


Plate  XI 


md 


^\i'j 


y 


1   ♦ 


r% 


r 


ABERRANT  COLORATIOX  OF  BROWX  TASSEL 

Toorly  flfveloped  tassels  of  brown,  tvpo  V    soin(.fini..v;  ,.vi,n,if  ,,        ,     •        , 
developed  parts  ^oiiKtinns  (.xinl.it  purple  m  al)norman.v 

(Drawing  by  Carrie  M.  Preston) 


Syracuse,  N    Y 

P*I  IAN.  21.  1308 


,    i  -  ,*A' 


